The Metropolitan Museum of Art

This is one of the best art museums in the world, and should be visited at least once. There are famous examples of basically every culture and time period's artistic expression on display. More than enough to see, and it would probably take a day or two to really appreciate the entire exhibited collection. If you are not a local, the admission is a little expensive. You really can't go to an art museum like this anywhere else in the country though, so I would argue it's worth it. If you love art and have a day in New York City, visit the Met!