what is the oldest building in new york city
says: 05/22/2015 at 11:09pm. The oldest COMPLETED building in Manhattan is not St. Paulâs Chapel, but rather the original house of the Morris Jumel Mansion, completed in 1765. Construction on St. Paulâs was begun a year earlier (1764), but finished a year later (1766) than the Morris Jumel Mansion.