There are two current photography exhibitions at the Metropolitan Museum of Art, After the Gold Rush and Photographic Treasures from the Collection of Alfred Stieglitz.  You should see at least one of these exhibitions.

The Metropolitan Museum of Art is located at 1000 Fifth Avenue (at 82nd Street).  For more information, see: http://www.metmuseum.org/visit/plan-your-visit/getting-here

The museum is closed on Mondays and open late on Fridays and Saturdays.  For more information, see: http://www.metmuseum.org/visit/hours-and-admission