Frank Lloyd Wright was an American architect known for designing over 1,000 structures in his organic architecture style. Some key points about Wright include that he believed structures should be in harmony with their environment, and that his most famous example of this was Fallingwater from 1935. He is also known for introducing the concept of "organic architecture," where structures respect natural principles and integrate harmoniously with their site and function. The Robie House from 1909 is cited as one of Wright's most famous works and a prime example of his Prairie School style, with its horizontal emphasis, brick and glass materials, and indoor-outdoor flow of space.