This lecture focuses on Frank Lloyd Wright’s mature works and explains his idea of organic architecture in greater depth. Using Fallingwater (1936) as the main example, the lecture shows how Wright designed buildings to exist in harmony with nature, not separate from it. It explains key ideas such as integration with the site, open and flowing interior spaces, use of natural materials, and the unity of form and function. The lecture discusses Wright’s innovative use of reinforced concrete cantilevers, inverted beams, structural mullions, and terraces that extend into the landscape, making Fallingwater one of the most important houses of the 20th century. It also covers concepts like plasticity and continuity of space, the merging of structure and skin, and the evolution of Usonian houses as affordable, human-scaled homes with simple plans, built-in furniture, and strong connections to outdoor spaces. Overall, the lecture helps students understand how Wright’s architectural ideas influenced modern housing and organic design worldwide.