This house was built partly over a waterfall on Bear Run in the Mill Run section of Stewart Township, Fayette County, Pennsylvania, in the Laurel Highlands of the Allegheny Mountains. The house was designed as a weekend home for the family of Edgar J. Kaufmann.
Time cited it after its completion as Wright's "most beautiful job", it is listed among Smithsonian's Life List of 28 places "to visit before you die.". It was designated a National Historic Landmark in 1966.
The Kaufmanns planned to entertain large groups of people, so the house would need to be larger than the plot allowed, and also the plot was not large enough for a typical Wright house. Also, Mr. and Mrs. Kaufmann requested separate bedrooms, as well as a bedroom for their adult son and an additional guest room. A cantilevered structure was used to solve these problems.
For the cantilevered floors, Wright and his team used upside-down, T-shaped beams integrated into a monolithic concrete slab which both formed the ceiling of the space below and provided resistance against compression.
This organically designed private residence was intended to be a nature retreat for its owners. The house is well-known for its connection to the site; it is built on top of an active waterfall which flows beneath the house.
The fireplace hearth in the living room integrates boulders found on the site and upon which the house was built — ledge rock which protrudes up to a foot through the living room floor was left in place to demonstrably link the outside with the inside. The stone floors are waxed, while the hearth is left plain, giving the impression of dry rocks protruding from a stream.
Integration with the setting extends even to small details. For example, where glass meets stone walls no metal frame is used; rather, the glass and its horizontal dividers were run into a caulked recess in the stonework so that the stone walls appear uninterrupted by glazing. From the cantilevered living room, a stairway leads directly down to the stream below, and in a connecting space which connects the main house with the guest and servant level, a natural spring drips water inside, which is then channeled back out. Bear Run and the sound of its water are part of this house, especially during the spring when the snow is melting.The design incorporates broad expanses of windows and balconies which reach out into their surroundings.
On the hillside above the main house stands a four-bay carport, servants' quarters, and a guest house. These attached outbuildings were built two years later using the same quality of materials and attention to detail as the main house. The guest quarters feature a spring-fed swimming pool which overflows and drains to the river below.
Wright had planned in the beginning to have the house blend in to its natural settings in rural Pennsylvania. In doing this, he limited his color choices to two colors, light ochre for the concrete and his signature Cherokee red for the steel.
