The CUNY Graduate Center used to be the B. Altman department store! It's on 34th and Fifth Avenue. The building is stupendous. It was gutted and done over to make it into an academic building, but lots of details have been retained and kept in good repair, including a skylight above the 8th floor cafeteria (which uses the same food service as the big magazine publishers do!) and this magnificent staircase in the library.