The Solomon Guggenheim Museum is located at the corner of East 90th Street and Fifth Avenue, in a stretch called Museum Mile (the stretch of that road hosts the Met Museum, the Museum of the City of New York, Guggenheim, among others).
The museum, which contains an extensive collection of Impressionist, Post-Impressionist, and modern art, was designed by the famed Frank Lloyd Wright. It opened in 1959.
Useful info: website: guggenheim.org. The museum opens at 10am and closes at 5:45pm. Tickets start at $18