1. Liggett Hall on Governors Island

The boundary to the southern half of Governors Island is marked by the stately Liggett Hall — a former military barrack that is as long as the Chrysler Building is tall. (Construction workers at the site keep their distance from the building; it is said to be haunted.) Designed by McKim, Mead & White, and built in 1929 at Fort Jay on the Island, the post was designed to house an entire army infantry. Today, it serves as a centerpiece of Governors Island Park.

For Open House New York,  its secret archway gymnasium will be open to the public for the first time.

Win an Open House New York VIP Weekend Passport from Untapped Cities and look back at the 10 Must-Visit Open Access Sites For NYC’s OHNY Weekend 2017 (No Reservations Needed).