1997

The tower was designed to rest on a continuous reinforced concrete mat, 4 feet thick, with the base of the slab 24 feet below street level.

What makes the Texas Commerce Bank Building revolutionary in the civil engineering world is not so much the building itself, but its foundation.  Initial studies for the type of foundation to be used began in the fall of 1927.  William E. Simpson, the building's chief structural engineer, suggested using a mat foundation, something new for Houston's multistory buildings.

After more than 50 years of contention and debate, dredging began in 1911 on an eight-mile channel connecting Puget Sound, Seattle's gateway to the Pacific, to two inland freshwater lakes, Lake Washington and Lake Union. With the completion of the Lake Washington ship channel and Chittenden locks, coal and logs from the interior had a dedicated water route to the ocean, and the city's 4 1/2 miles of coastal harbor burgeoned into 100 miles of commercial, industrial and recreational piers and wharves.  

The structure has two segments: an East Channel bridge consisting of four 175-foot spans and three 240-foot spans crossing from Harrisburg to City Island; and a West Channel bridge, consisting of seven 175-foot spans crossing from City Island to Wormleysburg.

With 15 truss spans totaling 2,820 feet, the Walnut Street Bridge is the finest and largest surviving example of the standardized Phoenix wrought-iron truss bridges produced from 1884 to 1923.

The scheme virtually reverses the flow of the Snowy River from its natural course toward the ocean and directs it inland. The entire complex includes 16 dams, seven power stations (with a production capacity of 3,740,000 kilowatts), over 90 miles of tunnels, a pumping station, and 50 miles of aqueducts.

The crossing of the Delaware River at Easton, Pennsylvania, provided a central link in travel from the northeastern seaboard to America's inland territories throughout the 18th and early 19th centuries. From 1806 to the mid-1890s, travelers used a landmark wooden structure built by noted bridge-builder Timothy Palmer. By the 1880s, however, Palmer's three-span covered bridge could no longer handle the demands of traffic generated by new trolley lines.

Navajo Bridge spans Marble Canyon, 470 feet above the Colorado River in Grand Canyon National Park. It was considered the highest steel arch bridge in America when completed.

The Navajo Bridge (also known as the Grand Canyon Bridge) was built in 1929 by the Arizona Highway Department and provided a vital transportation link over the Grand Canyon between northern Arizona and southern Utah. Construction commenced by building on one side of the canyon, then on the other, until the two sides met in the middle.

The massive Grand Coulee Dam, on the Columbia River, is the largest concrete structure in the U.S., the largest hydroelectric facility in the U.S., and the sixth-largest hydroelectric facility in the world. It provides irrigation for up to 1.1 million acres of agricultural lands and the hydroelectric complex maintains a generating capacity of 6.8 million kilowatts. It also serves as the primary flood control for the Columbia River basin (with a capacity of 5.18 million acre-feet of water) and provides recreational opportunities on the 150-mile-long Franklin D. Roosevelt Lake.

Gilman Hall, built in 1916-1917, accommodated a growing College of Chemistry by providing expanded research and teaching facilities for faculty and students specializing in physical, inorganic and nuclear chemistry. Work performed at Gilman Hall helped advance the fields of chemical thermodynamics and molecular structure, and has resulted in multiple Nobel Prizes. The Hall is most famous for the work of Glenn T. Seaborg and his coworkers, which included the successful identification and production the element Plutonium. Seaborg received the Nobel Prize in 1951 for his accomplishments.

In 1961, in the National Institutes of Health Headquarters (Bethesda, MD), Marshall Nirenberg and Heinrich Matthaei discovered the key to breaking the genetic code when they conducted an experiment using a synthetic RNA chain of multiple units of uracil to instruct a chain of amino acids to add phenylalanine. The uracil (poly-U) served as a messenger directing protein synthesis. This experiment demonstrated that messenger RNA transcribes genetic information from DNA, regulating the assembly of amino acids into complex proteins.