Kentuck Knob is a crescent-shaped one story Usonian house designed by Frank Lloyd Wright for the site in rural Stewart Township near Chalk Hill, in Fayette County Pennsylvania. The house, which is about 50 miles (80 km) southeast of Pittsburgh, was entered on the National Register of Historic Places in 2000. The house, also known in some architectural publications as the Hagen House, is sited on Chestnut Ridge, the western-most range of the Allegheny Mountains in southwestern Pennsylvania. It is recessed into the southern side of a 2,050-foot (620 m) high geological formation known locally as Kentuck Knob. It is located south of Pennsylvania State Route 2010 roughly four miles from Wright's internationally-celebrated Falling Water. It has a sweeping view of the Youghiogheny River gorge, although the view of surrounding hills and farmland has been somewhat enclosed by trees planted by the original owners, I.N. (Isaac Newton) and Bernardine Hagen, who owned the property until its sale in 1986 for $600,000. The second owner, Lord Palumbo, bought the house and grounds as a vacation home, but since 1996, the Palumbo family has combined part-time residency at Kentuck Knob with a public tour program in a manner reminiscent of the Great houses of Great Britain.
The Hagen House was begin in 1953, when Mr. Wright was 86 years old and in the final phase of his brilliant career as perhaps America's most celebrated and original architect. At the time, he was also at work on a dozen other residences and the Guggenheim Museum in New York City, and the Beth Shalom Synagogue in Elkins Park, Pennsylvania. The Hagens were natives of Uniontown, Pennsylvania and owners of a large dairy serving southwestern Pennsylvania and friends of the Edgar Kauffman family, for whom Mr. Wright had designed and built Fallingwater nearby. The purchased the 80-acre parcel of land and asked Mr. Wright to create a deluxe Usonian house. The house was completed in three years, and the Hagens lived their for the next 30 years.
The house is constructed of native sandstone, red cyprus and glass around a west-facing courtyard. It has a copper roof estimated to cost $96,000. It has a hexagonal stone core rising to the hipped room from the intersection of the living room and bedroom wings. On the eastern side of the courtyard, the flat-roofed carport fuses with the stone of the Knob and anchors the house to the site in the distinct manner characteristic of Wright's organic approach. To the south, the house extends out from the hillside on 10" thick stone-faced concrete ramparts. Kentuck Knob plan is designed on a module system using an equilateral triangle measuring 4'-6" to a side creating a modified L-plan house with a 240 degree outside angle.
The house is oriented to the south and west to capture the best light throughout the year, a feature Mr. Wright frequently used when not limited by the coordinates of a city lot. Mr. Wright also did not select the crest of the Knob, which would have provided more commanding views. Instead, he chose a more challenging and less obvious site, nestled into the side of the knob. This allows the house and grounds to appear harmonious with the landscape rather than dominating it.
Mr. Wright was typically meticulous, demanding and even tyrannical about any changes to his design by or for his clients, and Wright enthusiasts often struggle with efforts to retain the purity of his original visions following his death. In the case of the Hagen house, this involved not only the design of the visitor centre, but also the addition of a sculpture meadow that was not part of the original plan. The Palumbos have added the meadow with more than 30 works by contemporary sculptors such as Sir Anthony Caro , Andy Goldsworthy, and Ray Smith, as well as a collection of found art pieces include a French pissoir, red English telephone boxes, and a vertically upright concrete slab from the Berlin Wall. The meadow is reached by a walking path through woods from either the house or the visitors center.