The world's oldest hologram gallery and the labyrinthine laser laboratory of a holography pioneer.

From scholastic to sepulchral - now under reconstruction.

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

The oldest family-run luncheonette in New York, last renovated in 1948, still serves food and drinks the old-fashioned way.

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

Peek through the gates at this oasis from the city, full of Old English charm.

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

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

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

Become a prohibition rebel.

New York City's smallest piece of private property.

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

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

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.

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

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."

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

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

The remnants of a Gilded Age elegance preserved in the middle of a stark modern tower.

A men’s restroom became a sandwich shop.

No one messes with the Massachusetts sacred cod, not this time...

The quiet canyon has a tumultuous history involving a doomsday cult.

A Bicycle Path in the Sky.

These artworks take you traveling to mythical medieval Europe, the politicized grape fields of 1960s California, and deep below sea level.