Taliesin West was architect Frank Lloyd Wright's winter home and school in the desert from 1937 until his death in 1959 at the age of 91. Today, it houses the Frank Lloyd Wright Foundation, a school for architects, and is open to the public for tours. During his lifetime, Wright continually altered and added to the complex of buildings, all of which were constructed by students. The design was an organic response to a combination of driving factors: the rugged nature of the talus-sloped mountain site, from which Wright plucked the sand, gravel, and stone used as basic construction materials; the mild winter climate, which permitted natural lighting through a tent-like roof of redwood and canvas; the necessity of housing a community of staff and students. It is a U.S. National Historic Landmark. Restoration work to the private quarters of Mr. and Mrs. Wright was completed in 2004.