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

Nikola Tesla's former home contains an homage hidden from plain sight.

A tunnel once abandoned now thrives with graffiti art as an off-limits makeshift gallery.

Nondescript elevator doors open to reveal a stunning, surreal world.

This unmarked and unloved Manhattan subway grate created one of the most iconic images in American cinema.

A three-story copper skybridge connects two Manhattan buildings with Art Deco luxury.

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

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

More gold than anywhere else, ever.

The world’s oldest and biggest bookstore stocking only mystery, crime fiction, espionage, and thrillers.

New York's oldest magic store.

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

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

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

A crumbling hospital from the 1850s on Roosevelt Island.

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

This enormous banquet-themed artwork honors over 1,000 notable women throughout history.

A clock set into the concrete outside a Manhattan jeweler has been telling time underfoot for over a century.

Climb right into the heart of this colorful Iceland volcano.

Walk in the footsteps of the gods and straddle two tectonic plates.

Strange rock formations tower above the river that snakes through this enchanting Icelandic canyon.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

Europe’s most powerful hot spring supplies the surrounding region with hot water.

Along this wire fence, travelers have been leaving a particular memento since 2012.