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

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

New York City's smallest piece of private property.

This little museum is built on a theater that was once a wildly elaborate speakeasy.

A dilapidated dock tells the story of Titanic's missed arrival.

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

A semi-scholarly approach to sex.

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

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

A miniature rainforest is growing inside of a Midtown Manhattan office building.

Try not to get slimed in Tribeca.

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

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

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

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

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

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

A terrific purveyor of natural history objects and curios.

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

Where scientists keep miles of very valuable ice from Antarctica and Greenland from melting.

A technicolor place of worship for Elevationists.

This modern antique shop is a museum for 1980's Saturday morning cartoon culture.

A hundred-year-old museum filled with giant physics toys and experiments designed by grad students.

Nevada's largest cactus collection stands outside a candy mogul's small factory.