PHILANTHROPY: Collector No. I

In the spring of 1939 an imposing building was rising in Washington—the new National Gallery of Art, destined (it was hoped) to become one of the world's great repositories of culture, made possible by a gift from the late Andrew Mellon and a promise of perpetual maintenance from Congress. Before long, the gallery would open, with a great fanfare. Inside its vast walls of naked, flesh-colored Tennessee marble, the public would find a trove of masterpieces from the Mellon collection—such unparalleled works as Raphael's Alba Madonna, Botticelli's Adoration of the Magi. But...