One of the last great private American collections formed in the 20th century, this array of masterworks reveals a unique curatorial vision and true connoisseurship. Ranging from Old Master and Impressionist paintings through the contemporary period, highlights include major canvases by Rothko, Diebenkorn, O'Keeffe and Hopper. Explore Property from the Collection of Mrs. Paul Mellon: Masterworks online and in our New York galleries, beginning  31 October.