A Frank Lloyd Wright masterpiece, Fallingwater is south of Pittsburgh on Rte 381. Completed in 1939 as a weekend retreat for the Kaufmanns, owners of the Pittsburgh department store, the building blends seamlessly with its natural setting. To see inside you must take one of the hourly guided tours, and reservations are recommended. A more intensive two-hour tour, with photography permitted, is offered ($55; times vary depending on day and month, reservations required). The rather attractive forested grounds open at 8:30am.