Architect. He was a major 20th century architecture figure whose elegant buildings of cast concrete transformed the International Style of corporate modernism in a spiritual  direction. His first important work was the Yale University Art Gallery (1952 to 1954), completed while he was teaching architecture at Yale, from which he departed in 1957 to become Professor of Architecture at the University of Pennsylvania.  Among his later important buildings are the Salk Institute for Biological Studies in La Jolla, California (1959 to 1965) and the Kimbell Art Museum in Fort Worth, Texas (1966 to 1972).  Between 1961 and 1966 Louis Kahn collaborated with Isamu Noguchi on the design of a playground for Riverside Drive Park in New York City.He died of a heart attack in a bathroom in Pennsylvania Station in New York City. (bio by: MC)