American sculptor and artist Alexander Calder (1898-1976) in his studio in 1973. Trained as a mechanical engineer, Calder went to the Art Students' League in New York and then lived in Paris in the 1920s, where he became friends with avant-garde artists like Jean Arp and Marcel Duchamp. He invented the mobile and created abstract static sculptures that were dubbed stabiles. In the 1950s he moved into creating abstract monumental sculptures.