The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

A derelict bit of transportation infrastructure hidden in the woods.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

France's national museum of scientific and industrial instruments.

Indents in the pavement are all that remain from a grisly death machine in Paris.

Behind the pink curtain, Au Bonheur du Jour, an art gallery of erotic archives.

"In the Dark" Restaurant in Paris offers dinner in complete darkness.

This Parisian café sticks almost exclusively to an ethos of reuse.

A museum of magic with a Sadist past.

A counter-culture bookstore like no other hides in plain sight in the streets of Paris.

A haunting collection of the vanished and disappearing natural world.

A museum of carnival attractions where you are invited to ride the rides.

This massive library holds what was once the largest book collection in the world.

The macabre collection of Jacques Sirgent, an expert scholar on the undead and all of their trappings.

Remains of the old fortification along the Western border of the USSR, now an elaborate defense museum.

A small museum in this border city displays the contraband art that has been stolen back from smugglers.

Thanks to its heroic service during WWII this Soviet castle has been turned into a monument towered over by a brutalist titan.

A carousel trades in its classic horses and calliope for endangered species, native flora and fauna, and a modern soundtrack.

The L.A. Zoo has a secret garden of rare bootleg cycads, a palm specimen dating back 280 million years.

William Blake claimed to have painted this gothic masterpiece after encountering this nightmarish being in a vision.

A statue of the legendary Celtic warrior queen who fought the Roman invaders stands in one of the cities she once destroyed.

Revel in the Victorian splendor of the world's oldest eating establishment inside a museum.

Where condemned pirates met their grisly end at the gallows on the River Thames.

The 2,000-year-old beam is tucked within the pedestrian entrance to the old London Bridge.