“Kentuck Knob, also known as the Hagan House, is a residence designed by the American architect Frank Lloyd Wright in rural Stewart Township near the village of Chalk Hill, Fayette County, Pennsylvania, USA, 45 miles (72 km) southeast of Pittsburgh. It was added to the National Register of Historic Places in 2000” (From Wikipedia)
So you are visiting Fallingwater and your tour ends late morning or your tour does not start until afternoon. Take the time and go visit Kentucky Knob. It’s not far away from Fallingwater and it’s a very different experience.
Make sure to talk the art walk after the tour…it’s worth the walk.