In the late 1930s, Edgar Kaufman asked starchitect Frank Lloyd Wright to design a home near a waterfall in Pennsylvania — and an architectural icon was born. This summer, the Guggenheim Museum in New York (Wright’s last masterpiece) is presenting a retrospective of Wright’s work. As part of our American Icons series, Studio 360’s Peter Crimmins finds out why Fallingwater was named the best building of the 20th century.