Louis Kahn, renowned American architect, planned the construction of numerous civic structures. Among them was public housing, viaduct systems, and streets and roads in the city of Philadelphia. He did not arrive at his distinctive modernist style till he was in his fifties. His projects since this turning point include art museums, assembly halls and libraries; religious centers and parks; and the Salk Institute in La Jolla, California; and the National Assembly building in Dhaka, Bangladesh, considered the masterpiece of his career. His buildings are a concentration on space and material and weight, rejecting any overt loyalty to historical styles of architecture.