<human>:  When did Frank Lloyd Wright build the Usonian House?
<bot>: The Usonian House was built in 1949. It was designed by Frank Lloyd Wright and was the first house to be built in the Usonian style. The Usonian style is a modernist style of architecture that was popular in the 1940s and 1950s. It is characterized by a simple, functional design, with a focus on the use of natural light and open spaces.