The Rise Of The Skyscraper From The Ashes Of Chicago

Builders have striven for height ever since the Tower of Babel, but until the end of the nineteenth century the tall structure was a monument, a symbol of temporal or spiritual power, not the functional building we know today. That changed when from the ashes of the Great Fire of 1871 Chicago rebuilt itself as the most modern city in the world. Tall buildings were going up in other places then, too, but no other city made such a determined and sustained effort to build and define their use and form. There are a lot of reasons that the modern tall office building evolved only at that time and preeminently in Chicago. It’s a story that illustrates the complexity of large-scale technological development, and it also shows that some of the things we think we know about the birth of the skyscraper are myths. Here’s how it happened, how a number of necessary technologies emerged at once and coalesced as the skyscraper.

To begin with, although virtually the entire business center of the city and much of its wealth were destroyed by the fire, Chicago’s economic structure, based on trade, survived. Grain and cattle still poured into the city, the ships still docked, and the trains still ran, albeit with difficulty. Credit was therefore still good. Out of a total loss estimated at about two hundred million dollars, less than half was insured. From San Francisco to Maine and beyond to London, insurers lost a total of seventy-five million dollars. Fifty-one of them went into liquidation across America, including fourteen in Chicago that were completely wiped out. Chicago’s trade, however, rebounded.

With telephones, automobiles, and rapid suburban train systems still several decades into the future, Chicago’s businesses had little choice but to rebuild in the same concentrated downtown area, where communication was quick and direct. Land values increased. High structures were needed.

Chicago Construction

The city already excelled in building technology. Thirty years before the fire Chicago had taken the lead in developing a novel form of building called simply “Chicago construction” and, perhaps derisively, the “balloon frame.” So successful was it that it has dominated residential construction across North America ever since.

The balloon frame was remarkable. It evolved pragmatically, in small steps, not as a conceptual idea at all. The term frame is really wrong for it. Previously, framing had been characterized by heavy beams, posts, and diagonals, all interconnected by precise and rigid joinery. The balloon frame, depending on how you look at it, consists primarily either of thin panels with light “stud ribs” as stiffeners or of two-by-four studs and joists made rigid by boards laid on them; it comprises at any rate both studs and panels together. A panel can be prefabricated on the ground and raised into position, but then window and door openings can be made only where they will not interrupt a diagonal brace. But if the frame is built stud by stud, a hole can be made anywhere by nailing stud pieces to surround it. This flexibility is a key to the balloon frame’s universal success.

The balloon frame turns its evident weaknesses to its advantage. Before its development, the greatest impediment to construction in North America was the lack of trained craftsmen needed to form the intricate connections that make traditional heavy timber and half-timbered frames stand up. We had to make do with much more primitive connections. Nails do not hold as well as dowels, but they suffice if more are used, so there arose a technology in which the nail works by virtue of sheer quantity rather than through the quality of the individual connection. An individual nail or bolt can fail without endangering the whole just as traffic can be blocked on a Manhattan street crossing without causing the grid system to fail, and a nailed frame can transmit its forces in any number of ways.

Framing lumber is prefabricated in standardized lengths and sizes, but fine tolerances are irrelevant and quality control almost totally unnecessary. Brackets, connectors, and nails are so simple that the usual attributes of industrial prefabrication—precision and interchangeability of parts—simply do not apply. Lack of a need for quality in production is therefore actually an advantage. It saves labor and money.

Most of what burned down in Chicago in 1871 was built of wood and brick. The timber frames of the ruined city were decidedly empirical in design, but so were the cast-iron fronts that had been applied to brick and timber buildings. Plans remained the same whether or not the buildings had iron skins. No one had ever considered the conceptual possibilities of what had been developed. Before the fire Chicago had no school of architecture and few trained architects.

The city’s devastation created a vacuum, a gaping need for talent and ideas. When new builders began inevitably to arrive, most of them were European-trained. Their education had included analytical statics and materials technology as well as a conceptual and systematic approach to problem solving in the design of structures. The resulting clash between two modes of thought, a continental European conceptual approach to design and Yankee empiricism—both having obvious strengths and weaknesses—must have been invigorating. It had to be a shock for analytically trained minds to confront a freewheeling, uninhibited pragmatism that worked. Many of the new builders were demobilized Civil War engineering officers, who had gone from school to a profession via active military service, in itself a form of culture shock. They could not but realize the exciting aspects of what they met. By and large, what these men found in timber, they re-created in iron. That was the first step.

Beginning with Iron

Iron was an established structural material long before the Chicago fire. The French and the British, the world leaders in mechanics and metallurgy, had begun using iron in quantity at the end of the eighteenth century. The British preferred cast iron, which can be poured or cast in molds and is cheap to manufacture. Cast iron has a high carbon content—as much as 4 percent. Its production requires little metallurgical control, but like structural stone, cast iron is really useful only in compression. It fractures easily when subjected to tension, bending, torsion, or shearing forces. The French preferred wrought iron, a much more malleable, low-carbon metal. It can be forged or rolled into bars, columns, beams, or plates and withstands any type of stress well, but its manufacture demands great skill and expense. French industrial development, retarded by the Revolution and its aftermath, failed to thrive and influence America as the British did, and that is one of the reasons cast iron came to predominate here.

Iron internal structures for buildings were uncommon in 1871, but they did exist. Iron is fireproof, and French theater roofs and staircases and British mills had been built with an eye to fire safety. Gradually iron had begun to be used for other reasons, to build things that could not have stood up in any other material. The Palm House at Kew Gardens in London, built entirely of wrought iron in 1847, still survives. The architect Henri Labrouste finished a library building in Paris in 1850, the Bibliothèque Sainte-Geneviève, in which castiron columns and arches supported two barrel vaults forming a fantastic canopy under wrought-iron roof trusses. The fabulous Crystal Palace, built largely of cast iron and glass for the great London Exhibition of 1851, was emulated all over the world. Every large city wanted a crystal palace. Bridges and railway-platform sheds required ever larger and more sturdy spans, and these, too, were being built in iron.

By the middle of the nineteenth century, foundries in the United States were mass-producing elegant “fireproof” castiron fronts and selling them nationally. Chicago, like many other cities, had a cast-iron district before the fire. A few American buildings were even made completely of iron. Perhaps the oldest of these, a naval arsenal built by the founder Daniel Badger in 1849, still stands, in Watervliet, New York. The columns and beams are patented cast-iron members. The roof trusses are of cast and wrought iron, the cladding is of cast-iron panels, and the roofing of corrugated iron. It was a state-of-the-art building, similar in structural concept to the soon-to-be-built Crystal Palace. The columns sat on their footings without being fixed to them. Gravity was supposed to keep them from lifting or moving when wind struck the building. What stiffness the building had was provided by the roof sheathing and the cladding. Surprisingly it proved adequate. The warehouse stood stolidly for almost a century until World War II, when a naval engineer, perplexed that it could stand without diagonal bracing, stiffened both ends with massive steel frames. Today they contrast unpleasantly with the graceful original structure and testify mutely to the inadequacy of an unquestioning devotion to standard practice.

The contractor James Bogardus rocketed into prominence around 1850 with important new ideas about iron. He used the founder Peter Cooper’s new deck beams—the first rolled wrought-iron beams made in America—in the Harper & Brothers Building in 1854, in New York City. It had taken Cooper two years of costly experimentation to produce the beams, and Bogardus was the first to take advantage of them. The building was designed to replace one ravaged by fire the year before, and the publishers were eager to have a fireproof building at whatever cost.

If fire resistance was the major benefit of iron construction, stiffening and connections between the members were the chief problems. When Chicago burned in 1871, the iron industry, based in Pittsburgh, was just beginning to seek new outlets for its products. A post-Civil War recession in railway construction was beginning, and the slump intensified in the economic depression of 1873-74. The ironmongers saw their future in buildings.

Enter the Elevator

Although even ancient Rome had apartment houses that reached ten stories, buildings of more than five floors had always been rare and impractical. Even if they became much easier to build, they would remain almost useless until vertical transportation became effortless. In a commercial structure clients could not be asked to climb more than a single story, and that unwillingly. The tall commercial building awaited the efficient mechanical elevator.

Elevators first gained widespread use in New York. Elisha Otis obtained a patent for his safety system in 1853, and the iron-fronted Haughwout Building of 1857 in New York achieved fame as the first commercial structure to install an Otis. This made it possible to use all six floors for display and selling. The Fifth Avenue Hotel followed in 1859, using a competing system; the first office building to use a passenger elevator was the Equitable, on lower Broadway, in 1870. From then on all the floors of a building could be equally accessible, and the ten-story elevator building emerged as the first building type decisively determined in planning and use by its installations. By 1876, the year of the Philadelphia Centennial Exposition, the elevator building was commonplace.

Steam was the available form of energy for elevators, but it imposed limitations. The winding drums that drove steam elevators became ever larger and longer as building height increased. The stress to a cable from being wound from one end of a drum to the other effectively restricted building height to about ten stories. Steam systems also required considerable maintenance; someone had to clean, stoke, feed, and fire up the boiler early in the morning all year long, and the buildings needed coal cellars and ash disposal.

Hydraulic systems, driven by the pressure in municipal water mains, helped overcome many of these disadvantages. The British direct-plunger type, in which a piston went down as far as the car rode up, had existed since 1830. By 1867 vertical cylinders up to three stories high could raise a car up to twelve times their length, increasing the hypothetical building limit to thirty-six stories—far higher than any building then planned.

Electric elevators, invented by Werner von Siemens in Germany in 1880, were at first highly impractical. The motor had to be controlled by cutting resistance as speed built up, causing an unpleasant jerking motion, arcing, and rapid wear. Winding was still the only way to cope with any rotating motor until the introduction of the friction-wheel drive, an 1897 German invention. Electric machines remained slow, because high speeds could fuse the motor, until the variablevoltage Ward Leonard regulator, patented in 1891-92, made possible the direct control of the generator. Then the safe and quick elevator finally collaborated with the stiff steel frame to permit the ascent to Babylonian height.

The Birth of the Steel Frame

The engineer Charles Louis Strobel was perhaps the most important individual in the development of the high-rise steel frame in the United States. Originally from Cincinnati, he trained in civil engineering at the Royal Institute of Technology in Stuttgart, graduating in 1873. He missed service in the Civil War but found a job in 1873 as a draftsman for the Cincinnati Southern Railway and advanced to assistant engineer for bridge design the next year. He stayed with the company for four years before moving on to become chief engineer and vice-president of the Keystone Bridge Company, a business owned by Andrew Carnegie, in Pittsburgh.

Carnegie also owned iron mills, and in 1881 Strobel designed for Carnegie the first standardized rolled-wrought-iron sections and, more important, their riveted connections. His little “Pocket Companion of Useful Information and Tables, Appertaining to the Use of Wrought Iron … for Engineers, Architects and Builders” was the first manual of its kind; it contained diagrams of fireproof flooring systems, building frames, and other standardized plans. Strobel also developed the steel Z-bar column, a structural member with a section like a capital H with serifs, made of several plates and angles riveted together. This antecedent of the modern Ibeam was first used in Keystone’s Kansas City Bridge in 1886. No column in one piece could be rolled large enough to take the loads of the very tall buildings beginning to emerge in the 1880s; Strobel’s Z-bar column could. Its first use in a building was in Cleveland, by the Chicago architectural firm of Burnham & Root.

The year before the design of the Z-bar, Strobel had moved to Chicago as consulting engineer for Keystone and the other Carnegie companies there. He worked with several of Chicago’s celebrated architectural firms and then, in 1895, designed today’s ubiquitous wide-flanged steel beams (they were adopted by manufacturers only at a later date). From 1905 to 1926 he headed his own firm, the Strobel Steel Construction Company, specializing in buildings and bridges. Without the support of such an inventive steel specialist, none of the architects or local practicing engineers would have had the expertise to develop the high-rise frame, not even William Le Baron Jenney, who is usually erroneously credited with its invention.

The steel frame wasn’t invented; it evolved from many sources. Jenney’s main contribution was an educational one, for he trained many of the architects who designed tall buildings in Chicago, including Louis Sullivan, William HoIabird, Martin Roche, and Daniel Burnham. Jenney graduated in 1856 from the Ecole Centrale des Arts et Manufactures in Paris, a private school that also produced Gustave Eiffel, the man who rationalized iron construction into the modern system it still follows. After graduation Jenney went on to study art and architecture in Paris and in Italy, then returned home to work in various jobs until war broke out. He served as a captain in the Army’s Corps of Engineers until 1868, when he moved to Chicago. In addition to building up several firms, Jenney taught architecture at the University of Michigan from 1876 to 1880.

Jenney’s Home Insurance Building of 1885 has long enjoyed the reputation of being the first skyscraper, not because of its height—it was originally only a nine-story elevator building—but because of the presumed independence of its frame from the enclosing outer walls of the building. For a frame to stand by itself, the connections between the columns and the beams must be fixed, so that they can transmit bending forces without the help of the stiffening provided by masonry walls. Bending stiffness defines the modern structural frame. It permits the use of lightweight cladding and infill panels of structurally weak materials such as glass, and it provides complete flexibility in the organization of office space, because no area need be blocked by bracing or stiffening walls.

In practice, however, few steel frames can stand safely without some form of secondary stiffening—an elevator-and-stair core or a zone of specially braced frames. This has nothing to do with the fixity of the connections but with the so-called softness of large steel frames, a quality inherent in the material itself. Yet until quite recently the frame with stiff connections and a non-load-bearing curtain wall was considered by architectural historians to define the skyscraper.

A preserved remnant of the structural system of the Home Insurance Building shows it to have relied on simple postand-beam construction without fixity between the members. The columns were of cast iron, which can neither take much in the way of bending nor form stiff connections with the girders, and the connections themselves were simple bolts, rather than far stronger rivets. The fact that the first steel beams ever to be built into a building were used for a very few of the girders from the sixth to the tenth floor, possibly at Strobel’s suggestion, is often cited as proof that this was a “real” frame. But however novel this may have been, structurally it is insignificant, for the difference between wrought iron and steel, especially the impure Bessemer steel used by Jenney, is one of degree rather than of material character. Steel contains more carbon than wrought iron but less than cast iron. It is harder than wrought iron and can withstand larger stresses of the same type but rusts more easily and is more brittle, although this can be improved by the addition of small amounts of other metals.

Finally, even if Jenney’s “skin” of terra-cotta, brick, and stone was largely, although not entirely, hung on the frame, this, too, was not new. It had been done in the fire towers of James Bogardus and the warehouses of Daniel Badger, both of New York, in the 1850s and 1860s. In fact, even in ancient half-timber framing, the brick or rubble infill between the timbers is not self-supporting, but it does bear on the wood and does help stiffen the frame. The skin of the Home Insurance Building must have performed a very similar function in a very similar way.

According to the historian Gerald Larson, the origin of the assumption that the Home Insurance Building was the first true “skeleton” frame structure lay in a legal battle between a Minneapolis architect, Leroy Buffington, and several of the architects of Chicago. Buffington patented a frame system in 1888 and claimed he had gotten the idea from a book published in 1872 by the French architectural theoretician Eugène Emmanuel Viollet-le-Duc. Buffington then proceeded to sue the Chicago builders for patent infringement. His suit failed because the builders countered by establishing a prior claim. Jenney was the doyen of the development of high-rise buildings in Chicago, and his office had produced many of the city’s successful architects. It was logical to choose a Jenney building for the honor of primacy that had to be bestowed, and the choice settled on the Home Insurance Building, possibly even in good faith. Some historians consider the Manhattan Building of 1890, also by Jenney, the first “true” frame because it did away with selfsupporting masonry party walls. But it, too, had cast-iron columns that did not permit fixed connections.

By the end of the 1880s the fixed frame—a relative term, of course—was beginning to emerge as a structural type. In New York the first steel frame appeared in 1889. The first frame in Chicago made of riveted, built-up steel columns and beams of standard rolled shapes was that of the Rand McNally Building of 1889-90. That building had to withstand the weight of large rolls of newsprint and the vibrations of heavy printing machinery, which is perhaps why expensive steel columns were used instead of the usual castiron ones. Except for the party walls of load-bearing brick, which carried only their own load, this building seems to have had a true stiff frame in the modern sense. The architects were Burnham & Root. Corydon Purdy, the engineer for the steelwork, later wrote, “It was the beginning of the end of cast columns.” Further steel frames followed in Chicago: the Caxton Building of 1890, by Holabird & Roche, and, then, almost at once, the Reliance Building, by Burnham and the engineer Edward Shankland, Holabird & Roche’s Pontiac Building, and Jenney’s Fair Store. Between 1892 and 1894, as steelmaking technology advanced, steel prices in Chicago fell more than 50 percent, from sixty-four dollars a ton to less than thirty dollars. At last steel frames were affordable.

The project engineer for the Rand McNally Building was Theodore Starrett. With his four brothers Starrett introduced an important new element on the scene: the contractor. As contractors the Starretts were major agents in the rise and spread of the skyscraper. All but William, the youngest brother, were protégés of the architect Daniel Burnham, who continued the educational role of his own mentor, Jenney. Two of the brothers became presidents of the George A. Fuller Company, which built many of the famous Chicago buildings. Another formed the Thompson-Starrett Company, in New York. A fourth, who remained in Chicago, headed the Starrett Building Company. So great an expertise did these men have that most of the tall buildings built in the United States until the middle of this century bear their imprint in some way.

Fireproofing and the Curtain Wall

The Great Fire of 1871 proved conclusively that incombustible structural materials did not guarantee a fireproof building. New, supposedly fireproof edifices such as the Chicago Tribune Building, sheathed in stone and boasting iron girders and joists, collapsed in the conflagration. So did the many cast-iron-fronted buildings. Research and development in fireproofing concentrated in two areas after the fire: the sheathing of iron structures and the creation of incombustible floors. Terra-cotta, an ancient fine-grained, brittle tile, became the choice for both purposes. Legend has it that during the fire the Chicago architect John Van Osdel buried his records in a basement floor covered with sand and damp clay. Their survival suggested to him fireproofing with clay tile. His Kendall Building of 1873 had clay-tile interior partitions and hollow-tile floor arches and was considered the first truly fireproof building in Chicago.

The protection of columns with terracotta cladding soon became standard. The first Chicago frame to be so clad was Holabird & Roche’s Tacoma Building, of 1889. Then followed the steelframed Rand McNally Building, of 1890. Terra-cotta fireproofing was to be abandoned only after the earthquake and fire of 1906 in San Francisco, where the brittle material fractured and thus failed to protect the steel frames beneath.

The sheathing of columns in terra-cotta soon led to the covering of whole building surfaces in that material. Since terra-cotta is a non-load-bearing material, it had to be hung on the frame, meaning that it needn’t carry even its own load. Such cladding could be divided into separate zones, allowing great flexibility in the appearance of the surface of a building. Light and air were criteria of the practical-minded clients in Chicago, and the curtain wall allowed designers to open up the enclosing skin to the utmost.

Since each floor height of a building’s terra-cotta cladding was structurally independent of the ones below or above it, the upper ones could be built before the lower, which could even be left out altogether. Stone could be suspended in midair. The same flexibility applied to interior partitions, so floor plans were likewise independent of what occurred above or below. The first Chicago building of a true curtainwall construction, excepting again party walls, was the Tacoma Building, designed by Holabird & Roche and the engineer Carl Seiffert, in 1889.

Two problems were raised by separating skin and skeleton: load bearing, which was resolved by the frame, and stiffening. It was believed that stiffening, too, had to be taken away from the skin, but while so dividing functions may be intellectually satisfying and conceptually clear, it is wasteful. It is diametrically opposed to the pragmatic solution earlier adopted for the balloon frame, in which the skin serves as cladding and stiffening at one and the same time.

In reducing the skin of a framed building to mere cladding, the problem of wind stiffening was exacerbated. Far too little attention was paid to this problem in the early years of the tall frame. The Home Insurance Building and many of its contemporaries had no clear provision for wind loading. Their walls, interior cross walls, and the stiffness of the cladding together kept them standing. Good engineers, however, soon began to perceive a serious problem. Perhaps the first to realize that the matter was a conceptual one was Jenney. His Manhattan Building, of 1890, was the first sixteen-story building in the world and the first tall building in Chicago without party walls—a distinction that may have led him to focus on wind loading. Jenney systematically stiffened the frame of the Manhattan Building with diagonal “sway rods” crisscrossing many of the frame bays. But the diagonals interfered with floor plans. His next design, the Isabella Building, of 1892, therefore used knee braces instead. These are short diagonals connecting the upper part of a column with the near part of the girder at an angle of forty-five degrees. Many more are needed, but they are less of a hindrance to planning than are sway rods.

The work of Corydon Purdy contributed greatly to the advance of stiffening in steel frames. Purdy, the engineer of the Rand McNally Building’s steel frame, was quite consciously an engineering designer and participated actively in the creation of the buildings he worked on. His ingenious design for stiffening the Venetian Building, of 1892, involved the addition of horizontal struts parallel to the girders under the floors but just above the suspended ceilings. These struts both strengthened the frame’s corners and served as connecting points for diagonal bracing. By then shifting the diagonal bracing system vertically to connect with these struts, he could leave room for doors adjacent to the columns instead of blocking an entire panel with corner-to-corner diagonals.

But Purdy’s solution still didn’t afford complete flexibility. That was achieved in the second Monadnock Block, of 1893, which he designed in collaboration with Holabird & Roche. There, Purdy used a portal frame, a joint that integrates the knee brace into both the column and the girder. It thickens a corner to produce a monolithic frame but frees up almost the entire panel surface, providing a large, arched opening. The chief disadvantage of this solution was that it made horizontal ductwork difficult, because the ceiling area close to the columns was blocked. Others tried different systems. In the Reliance Building two years later, Edward Shankland used tall plate girders and trusses riveted to columns to form portal frames much like the common systems of today, and he used sway rods for additional stiffness. This finally permitted the horizontal ductwork—wiring and such—to be led through open trusses.

Advances Underground

Downtown Chicago has very poor soil conditions, so as buildings began to get taller, attention had to be paid to the development of good foundation systems. As late as the 1890s new buildings sometimes slipped dangerously. The fivemillion-dollar Federal Building, built in 1880, settled so badly that it had to be condemned and demolished in 1898. As William Starrett wrote in 1928, “it was not uncommon for large buildings to be as much as three or four inches out of plumb, a condition frequently noticeable in the chatter of the elevators. It was a general practice then to allow for as much as a foot of settling, and sidewalks were canted upward from the curb line at as much of an angle as the builder dared, in the hope that, when the building did settle, the sidewalks would sink with it to their true plane. The extent of the settling, unfortunately, had to be guessed at.”

This condition was complicated by the height of the water table, which lies just ten to fifteen feet under downtown, limiting buildings to one basement level. This vexed the engineers, for a full, open basement story was generally needed just for a building’s heating system, janitor spaces, and elevator motors. (The ground floor had to be kept free for entranceways and lobby and retail space.) At first the standard pyramid-shaped stepped foundation in cut stone was refashioned for use under individual columns. The first were installed in the six-story Borden Block, of 1880, by the architect Dankmar Adler. But these occupied too much space to allow good use of the basement area, and as the height of buildings increased, so must the height and width of their stepped foundations. This effectively put a strict limit on potential building size.

The solution was the invention of the grillage foundation, in which a raft of two superimposed layers of iron rails, running at right angles to each other, spreads a column load over a large subsoil area through bending rather than through compression. Since iron resists bending stresses, the grillages didn’t deflect much, so only three to four feet of construction height was needed. The first incomplete version of the grillage was tried under several footings in Burnham & Root’s Montauk Building in 1882; the first fully developed ones were used in the Phoenix, or Austin, Building and the Rookery Building, both designed in 1886 by the same architects. Theodore Starrett, the future contractor, was a young draftsman at the time and is credited with coming up with the idea. The grillage was gradually improved upon, and steel rather than iron was used beginning in the Tacoma Building in 1889. From that day to this, the steel-beam grillage has remained the standard column foundation for tall buildings.

An ingenious form of foundation-excavation technique, the caisson system, also facilitated the rise of the skyscraper. Pneumatic caissons are essentially gigantic cups placed upside down on the surface of the earth. A building’s foundation is built on top of a cup, while workmen inside dig the watery soil out from underneath. The cup gradually lowers under the weight of the mass above it, but compressed air, pumped in from above, prevents water and mud from forcing their way around the lip and up into the cup. When the foundation is deemed deep enough, or when a load-bearing stratum has been reached, the workmen withdraw through the tube through which they and the air they breathe entered (and through which excavated dirt left). Then the cup and tube are filled with concrete, and the foundation is complete. This permits far more solid foundations through soft soil than had ever previously been possible by driving piles. The caisson was developed first for mining and then for bridge piles in France between 1839 and 1857 and was used in the United States for the first time in the construction of the Mississippi Bridge in St. Louis in 1874.

The pneumatic caisson was introduced to Chicago in 1893 by William Sooy Smith and his son, Charles, for foundations of the Chicago Stock Exchange Building. Smith had graduated in 1853 from West Point, which had adopted the French academic system and even used translations of French textbooks from the Ecole Polytechnique. His son had studied in Dresden and elsewhere in Europe. Smith also introduced to Chicago the technique of timber (later concrete) piling to reach firm ground as far as fifty feet below the surface.

Beyond Chicago

Not everything happened first in Chicago, of course, even though things did coalesce there. New York was also an important center for skyscraper innovation. The A. T. Stewart store, built in New York in the 186Os, was the first large metropolitan department store and was built completely of iron. When it was destroyed by fire in 1956 (it was by then a Wanamaker’s store), the historian Carl Condit noted that its cast-iron columns wer& continuous and its wrought-iron girders laterally attached to them. This gave a degree of semifixity to the connections far superior to what was usual before steel columns became common. We do not know how many other buildings benefited from similar detailing.

Cast-iron columns continued to be used for smaller highrise structures right into the beginning of the twentieth century. Cheaper than steel, cast iron was especially favored for speculative residential construction. The weight of a building accounts for most of the structural load in buildings of low to moderate height, whereas wind loads are greater in tall buildings. Builders hoped that cast-iron columns, taking chiefly compression caused by weight, would suffice. Usually they did. But the collapse of the almost completed frame of the thirteen-story Darlington Building in New York on March 2, 1904, proved the folly of disregarding horizontal forces, especially wind loading, or eccentric, off-center loading of columns, which can cause bending in frames. The Darlington disaster hastened a change in codes that thenceforth banned the use of structural cast iron. This accident was thus probably the final step in the creation of the modern stiff frame. What, according to Purdy, had begun in the Rand McNally Building in 1890 was completed by the collapse of the Darlington fourteen years later.

The high-speed elevator, the fixed-frame connection, reliable foundations, and modern heating and ventilation systems have made possible today’s high-rise structures, and gradual improvements have steadily occurred in all these, but no radical change has taken place in this century except for the introduction of the air conditioner, which permitted the extreme glazed curtain wall, at a great cost in energy.

Radical changes may be on the way, however. In the 1960s reinforced concrete began to be introduced as a common material for frame construction in this country. The first concrete frame in a tall building was that of the Ingalls Building of 1902, in Cincinnati, erected under license from the Anglo-American reinforced-concrete pioneer Ernest Leslie Ransome. Since then concrete has been used in Europe and Latin America whenever it was cheaper than steel.

Novel tubular structures for buildings—in which a building’s frame is essentially a big tube—began to be developed in the Chicago office of the firm of Skidmore, Owings & Merrill in the 1950s. These, like so much else in tall buildings, have their roots in nineteenth-century bridge designs. A kind of pierced tube of tightly serried columns and spandrels forms the frame of the concrete Brunswick Building, in Chicago, of 1965, as well as the steel John Hancock Center, in Chicago, of 1968. The World Trade Center and the Sears Tower are similar, and all these buildings once again utilize their exterior surfaces for load bearing and stiffening, thus obviating most interior structure and solving much of the dilemma created at the birth of the skyscraper.

The newest development in structural systems for highrise construction is the space frame, a three-dimensional triangulated structure, originally conceived in 1940 as a longspan roof for airplane hangars by the German immigrant engineer Konrad Wachsmann. It has reappeared in the “megastructures” of the British group Archigram, and elsewhere.

Who Invented the Skyscraper?

Invention is usually complex, and history is as mutable as the criteria we apply to our questioning. The facts may be incontestable, but evaluating them can be like judging a view while walking along a river. From any position the opposite shore presents a landscape, looking back in time, across at the present, and downstream to the future. As we move along the bank with time, we see the same landscape from a different angle with each moment. Objects loom large and then shrink away. Things we thought we knew intimately appear entirely new from a different angle. Thus history has to be rewritten from time to time, in order to remain relevant to the current viewpoint.

And so it is with the history of tall buildings. To begin with, where do we begin? Does skyscraper history originate with the stiff frame, with lightweight cladding, with the elevator? The answer depends on our point of view. Is the adoption of modern steel the turning point for the development of the stiff frame, or is the abandonment of the cast-iron column? The answer to both is, of course, yes, which makes it very difficult to locate the beginning of tall-building construction as we understand it today. Was or is the curtain wall of legitimate interest in this development? All the answers depend more on the interest of the questioner than on any absolute truth. But that doesn’t make them any less interesting; they determine a chronology not only of invention but also of changing values and of our understanding of engineering culture.

Chicago was one of the places where many developments came together at once. It wasn’t the only center, but it will always be central to a history of the building type that defines our age.