The famous American architect known for his designs in organic architecture is Frank Lloyd Wright. Wright developed a unique style that harmonized buildings with their natural surroundings, emphasizing the relationship between architecture and nature. He is best known for iconic structures such as Fallingwater and the Guggenheim Museum in New York City. His philosophy of Prairie Style architecture focused on open spaces and horizontal lines, moving away from traditional European influences. Wright's innovative approach revolutionized American architecture, and his principles continue to inspire architects today.