Mr. Marcus collected art and books. His favorite artists from Mexico were Rufino Tamayo, David Alfaro Siqueiros, Diego Rivera, and Antonio Ruíz. He became friends with Rivera and Tamayo. Mr. Marcus also liked American artists, such as Alexander Calder, who made sculptures, and Georgia O'Keeffe, who was a painter. He gave large amounts of money to a museum that showed O'Keeffe paintings.