Frank Lloyd Wright's 1939 cantilevered house over a Pennsylvania waterfall — domestic architecture's defining 20th-century moment.
From Wikipedia
Fallingwater is a house museum in Stewart Township in the Laurel Highlands of southwestern Pennsylvania, United States. Designed by the architect Frank Lloyd Wright, it is built partly over a waterfall on the Bear Run stream. The three-story residence was developed as a weekend retreat for Liliane and Edgar J. Kaufmann Sr., the owner of Kaufmann's Department Store in Pittsburgh. The Western Pennsylvania Conservancy (WPC), which has operated Fallingwater as a tourist attraction since 1963, maintains 5,000 acres (2,000 ha) surrounding the house.