Long the exclusive domain of birds and vagabonds, this little-known Central Park peninsula is open to the public once more.

During the holidays, a vintage subway train whisks New Yorkers back in time.

Unique antiquarian shop specializing in globes, maps, and prints.

An unassuming secret door once led to a legendary watering hole.

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

The original toys that inspired the beloved children's stories are on display at the New York Public Library.

A hands-on traveling collection of the innovative devices of yesteryear.

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

The feral felines of Roosevelt Island have a small army of allies and an abandoned hospital all to themselves.

A semi-scholarly approach to sex.

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

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

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

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

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

These old stone ruins in the Oregon wilderness were once bathrooms and are steeped in legends of murder.

Bring your own cardboard to the slippery slopes of concrete hidden in a neighborhood park.

On the Oregon coast there is a natural hole that seems to be draining the sea.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.

Most-visited and most-photographed slot canyon in the American Southwest.

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

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

Rippling sand dunes frozen in the Arizona rock.

A peculiar mansion built by the troubled heir to the Winchester Rifle Company fortune.