César Pelli (born October 12, 1926), founder of Pelli Clarke Pelli, is an Argentine American architect known for designing some of the world's tallest buildings and other major urban landmarks. In 1991, the American Institute of Architects (AIA) listed Pelli among the ten most influential living American architects. His many awards include the 1995 AIA Gold Medal which recognizes a body of work of lasting influence on the theory and practice of architecture. Perhaps his most famous work are the Petronas Twin Towers, which were for a time the world's tallest buildings. He also designed the World Financial Center complex in downtown Manhattan.