Ieoh Ming Pei (born April 26, 1917), commonly known as I. M. Pei, is a Chinese American architect. In 1948, Pei was recruited by New York real estate magnate William Zeckendorf. There he spent seven years before establishing his own independent design firm I. M. Pei & Associates in 1955, which became I.M. Pei & Partners in 1966 and later in 1989 became Pei Cobb Freed & Partners. Pei retired from full-time practice in 1990. Since then, he has taken on work as an architectural consultant primarily from his sons' architectural firm Pei Partnership Architects. His first major recognition came with the National Center for Atmospheric Research in Colorado; his new stature led to his selection as chief architect for the John F. Kennedy Library in Massachusetts. He went on to design Dallas City Hall and the East Building of the National Gallery of Art.