This beautiful building in the heart of Manhattan's Financial District was empty for decades.

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

A favorite Paris bar for U.S. expats, including Gershwin, Hemingway, and James Bond.

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

The celebrated eyesore created by starry-eyed sweethearts.

The very center of Paris is surrounded by a bevy of strange good luck rituals.

Notorious artist squat renovated into legal studios.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

New York's oldest and possibly grandest keeper of books.

This semi-hidden Manhattan restaurant is based out of a loading dock.

A very classy 1920s-era bar right in Grand Central Station.

Great place to have a drink and a bite to eat in an atmosphere laden with New York's Bohemian past.

A historic 1890s architectural masterpiece with an iconic clock tower that, once open to the public, now faces an uncertain future.

A legendary speakeasy bookstore returns from the brink.

Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

Hidden in an ordinary Midtown building is a one-room museum dedicated to the greatest escape artist.

A New York garbage depot holds a secret collection of weird and wonderful refuse.

A room in New York City that contains 250 cubic yards of dirt worth a million dollars.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

A Pythagorean funhouse that tries, successfully, to prove that math is the coolest thing ever.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

Tucked in the back of this amazing antique store is an important piece of medical history.

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