A modern zoetrope on the New York City subway.

This innocent-looking townhome is actually a subway exit.

Ride the subways of yesteryear.

The oldest living organism in New York City. Maybe.

This Queens hospital has stood abandoned for almost 20 years after its patients were secretly relocated in the dead of night.

A once crucial portion of the Long Island railroad still lays abandoned, waiting to be turned into an urban park.

This abandoned seaside fortress is now simply an imposing ruin being taken back by nature.

The crown jewel of the Queens Museum is a nearly 10,000-square-foot architectural model of the city originally built for the 1964 World's Fair.

Read between the lines of the subway map to find the hidden abandoned Civil War fort.

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

The loneliest island in New York.

Home to the infamous "Typhoid Mary" and the worst loss of life in New York's history prior to September 11, 2001.

A Gothic-style abode built to accommodate the church's three resident peacocks.

This plot of old-growth forest is the largest surviving remnant of New York City's original woodland.

Now abandoned, the first public health hospital in the U.S. saw more than one million immigrants from around the world.

This giant boulder is sandwiched between apartment complexes in upper Manhattan.

A sculptural commentary on capitalism pokes up from the East River.

Connecticut's shot tower is near the end of its life.

Once connected to the outside world by a single train track, this ghost town is looked after by the National Park Service.

Twenty-three trees, each paired with a basalt stone, line a street in Chelsea, continuing an urban project started by German Fluxus artist Joseph Beuys.

This simple Manhattan salt house is artfully shaped... well, like a giant granule of salt.

Play heads or tails with thousands of different coins.

A quiet and contemplative oasis in the middle of New York's bustle and riot.

The beautiful tunnel that ran from the lobby to Penn Station is still hidden underneath 34th Street.