On Oct. 21, 1959, the Solomon Guggenheim Museum opened on 89^th Street and Fifth Avenue, looking like nothing else anywhere. Its architect, Frank Lloyd Wright, modeled it after the ancient ziggurats of Mesopotamia, but critics likened it to an upside-down cupcake, a hot cross bun, a ball of mud. Still, it was the dawn of the jet age and the space race, a year of enchantment with the new, and people flocked to the spectacle. The first Sunday after its opening, 10,000 stood in line for hours to get in. One million visited the museum in its first year, 750,000 in each of the several years that followed. Critics have since come around. Back then, Ada Louise Huxtable rebuked the Guggenheim in the New York Times as "less a museum than … a monument to Frank Lloyd Wright." But this month, in the Wall Street Journal, she hailed it as proof "that great art and great architecture can coexist."