Farnsworth House near Plano, Illinois, was designed by Ludwig Mies van der Rohe as a weekend retreat for Edith Farnsworth and completed in 1951. One of only three private residences he designed in the United States, it became a landmark of modern architecture for its radical simplicity: steel columns, flat floor and roof slabs, glass walls, and an open interior organized around a central service core. Built on a floodplain above the Fox River, it faced recurring flooding and practical shortcomings, while rising costs led Farnsworth and Mies to sue each other. Later restored and opened to the public, it now operates as a museum.