THE BRONX-WHITESTONE Bridge has long been New York City’s least charismatic major span. One reason is that it connects two resolutely untrendy boroughs, the Bronx and Queens. But another reason is the way it has repeatedly been strapped in and buckled up for safety through the years. Underneath it all lies a beautiful bridge, but the effect has been like dressing Heidi Klum in a snorkel coat and galoshes. Now, however, the bridge is being stripped down to something resembling its original designer attire.

The Bronx-Whitestone opened in 1939, at the height of the fashion for slender, elegant suspension spans. That fashion came to an abrupt end the following year, when the Tacoma Narrows Bridge shook apart in a heavy wind. In response, the Bronx-Whitestone was retrofitted with diagonal stays between its towers and deck. In 1946, after these proved inadequate, the roadway was widened and clunky steel trusses were added on each side. And in 1988 a 94-ton tuned mass damper was installed to counteract the continuing problem of swaying in strong winds.

The alterations not only destroyed the bridge’s clean lines but also added lots of weight, increasing the strain on the suspension cables. Now advances in materials science are making it possible to solve both problems. The stays and trusses have been replaced with wind-deflecting fairings made of fiber-reinforced polymer, which are smaller and much lighter. The roadbed, formerly made of heavy crossbeams embedded in a thick layer of concrete, will be replaced with a lighter steel plate. And a thin coating of epoxy will replace several inches of asphalt on the road surface.

This spring the city celebrated the sixty-fifth anniversary of the bridge’s opening. The new fairings were all in place, allowing a much better view for motorists making the crossing. The other projects continue, and by 2006, if all goes well, the renovations will be complete and the bridge will be stronger and lovelier than it has been for decades. Heidi Klum should be lucky enough to look this good at age 65.

In Manhattan, meanwhile, the Skyscraper Museum has finally found a permanent home after nearly a decade spent living out of a suitcase in a series of temporary lodgings. The museum is located on the ground floor of the Ritz-Carlton Hotel in Battery Park City, on the edge of the skyscraper-dense financial district. It’s a compact collection, displayed in a single room, though the mirrored floors and ceilings create the impression of great height. A visitor will find construction photographs, working documents, beautifully illustrated old books, and exhibits on towers from the Sears Building to Shanghai’s Jin Mao Building, the tallest in Asia.

Perhaps most fascinating is the opening display, in which prominent architects give their definitions of the word skyscraper . It’s not clear what this says about national characters, but Renzo Piano, of Italy, exuberantly writes, “ THE ONLY WAY TO GO UP TO BREATH FRESH AIR IN THE MIDDLE OF THE CITY! ,” while Lord Foster of Britain is far more restrained (”a building or structure which is tall relative to its time and context”) and an assortment of Americans are long-winded and poetic in varying degrees. For information on the Skyscraper Museum, see www.skyscraper.org .

And while soaring bridges and a spiky skyline are often used as graphic shorthand for New York, the true essence of the city lies underground, in its 722 track miles of subways. The city’s subway system will celebrate its centennial this October, and one of the better short books being published to mark the occasion is Subways: The Tracks That Built New York City , by Lorraine B. Diehl (Clarkson Potter, 128 pages, $18.00). With memorabilia such as sheet music and Miss Subways posters as well as old maps, photographs of long-closed stations, and chapters on New York’s now-vanished trolleys and elevated trains, the book provides a fine, concise guide to how the subways were conceived and built and how they came to symbolize and typify life in America’s biggest city.