3. Inside the Arch There Used to be a NYC Parks Office

One of the most elusive urban exploration feats is getting inside the Washington Square Park Arch. It’s also one of the locations to have Guastavino tiling, the distinctive artisan tiles you’ll recognize from Grand Central Terminal, the original City Hall subway station, Ellis Island and other civic spaces throughout New York City. The Wall Street Journal got a glimpse inside the vaulted attic space, which is illuminated via skylights and electricity. It was once used as a New York City Parks office. Then, the staircase continues to the roof, which is accessible via skylight doors.

In 1917, painter John Sloan, Dadaist Marcel Duchamp and three of their friends broke into the interior staircase of the arch. They climbed to the top, cooked food, lit Japanese lanterns, fired cap pistols, launched balloons and declared it the independent republic of New Bohemia. The citizens were outraged and the interior door of the arch was sealed.

As for public access to the space, don’t keep your hopes up: “We don’t allow people up here,” John Krawchuk, the New York City Parks Department’s director of historic preservation told the Wall Street Journal, “The stairway is quite dangerous and the roof is quite fragile. If we allowed the public up here, the roof would fail quite quickly.”