An 1883 schoolhouse now home to collective of artists.

This futuristic airport terminal was abandoned for decades before reopening as a hotel—with a vintage plane of its own parked out back.

Just your average Marie Antoinette–themed speakeasy in an abandoned 19th-century subway tunnel.

This hidden library of physiological ephemera contains centuries worth of knowledge on the vim and viscera of the human body.

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

This former Norwegian sailor's church is slowly being taken over by ramshackle robot musicians.

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

The oldest surviving synagogue in New York City is now a soaring art space.

The haunting, dilapidated remains of a former poorhouse on Staten Island's Greenbelt.

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

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.

This lower Manhattan bar is set up in an old bank vault that rests beneath a skyscraper that hides even more historic splendor.

A treasure trove of artifacts, books, and artwork from the "golden age" of exploration.

Amid the bustle and noise of the Financial District hides a secluded garden oasis above the city streets.

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

Site of a former hidden treehouse in New Orleans.

An otherworldly musical haven in The Big Easy.

It's clear this abandoned Art Deco gem was no ordinary cleaners.

An impressive collection of dollhouses and an homage to the frog-leg canning industry.

A pink cottage covered in hearts served as a haven and a resting place for LGBTQ activists.

The crumbling remains of a 19th century fortess.

Storyville was New Orleans' historic red light district and hotbed of jazz music, sometimes referred to simply as "The District."

According to one local tradition, the entrance to the Voodoo underworld can be found in New Orleans through seven gates scattered throughout the city's French Quarter.