Founded in 1939, this contemporary art pioneer is now housed in a Zaha Hadid–designed concrete-and-glass structure Downtown; with no permanent collection, the 80,000-sq.-ft. museum hosts temporary exhibitions and installations that range from drawing and painting to sculpture, photography and video; there's also a performance space and a floor – dubbed the UnMuseum – dedicated to interactive, touchable art; N.B. free on Mondays from 5–9 PM.