Major repairs, which were completed in 2002, prevented fallingwater, the only Frank Lloyd Wright house with its original furnishings intact, from collapsing into the stream that runs through it.

Frank Lloyd Wright was 67 years old—considered well past his prime—when a wealthy Pittsburgh department store magnate named Edgar Kaufmann commissioned him in 1935 to design a weekend house in western Pennsylvania. Looking at Wright's initial plans, most engineers said it wouldn't stand. Even Kaufmann was taken aback when Wright first showed him the plans. What a crazy idea, cantilevering three levels of the house out from the side of a hill, letting a waterfall tumble right beneath the terraces! The old man must really have lost it, his doubters muttered.

Yet it turned out to be one of the most famous and influential house designs of the 20th century; recently the American Institute of Architects voted it the "best all-time work of American architecture." It sparked not only a late-in-life resurgence in Wright's career, but a whole new Modernist style of architecture. The house—appropriately named Fallingwater—seems a flat-roofed series of sandstone ledges magically carved out of the hillside rather than appended to it, with extensive windows and terraces everywhere to dapple the interior with light from the surrounding woods. Wright's principle of harmony with nature never was more perfectly expressed than in this house.

Those engineers were partly right, though. After more than 60 years, this national architectural treasure required a major effort to stabilize the main cantilever, reinforce the poured concrete foundation, and strengthen the flagstone and redwood floors with steel girders. Without those repairs, which were completed in 2002, Fallingwater might have collapsed into Bear Run, the cascading stream that runs through it.

Fallingwater is the only major Wright residence available for tours which still has all the original furnishings intact. This is important because Wright's vision included furniture (both built-in and free-standing) that he designed specifically for the house, right down to lamps, hassocks, and rugs. The stone hearth in the living room was built from boulders found on the site, some of them simply protruding through the floor from where they'd originally stood. Because the house remained in the Kaufmann family until it was donated in 1963 to the Western Pennsylvania Conservancy, it also has all of their books, objets d'art, and an art collection including work by Audubon, Tiffany, Diego Rivera, and Picasso. Walking through Fallingwater, you get a visceral feeling of Wright's low-slung aesthetic, from the teeny-tiny bedrooms he insisted on to the low ceilings (they never bothered the 5-ft., 5-in. architect). Wherever you are in the house, stop for a moment and listen—you'll be able to hear the waterfall burbling below.

Make tour reservations in advance; few are offered in the winter months.

Copyright © 2009 by John Wiley & Sons, Inc. All rights reserved.