A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

This forgotten boat elevator was an engineering marvel in its heyday.

The towering figures were created from the cemetery's fallen old-growth trees.

An easily overlooked memorial to a Ukrainian famine-genocide that killed over 4 million people.

An overlooked oasis of quiet on the grounds of Washington's monumental basilica.

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

There’s a hidden military meme engraved on the World War II Memorial.

People escaping slavery may have hidden inside a corpse vault.

A historic estate packed with George Washington's heirlooms, and its own nuclear bunker.

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

The mystery of this small, brick pond eluded its possibly only investigator until his death.

Fantastically decorated underground chambers built in the 1760s.

This haunting stone chasm is a hotbed of mossy rock and English legend.

A sweet symbol marks the place where torturous executions were once carried out.

A statue in the heart of Edinburgh honors a bear that served in the Polish military during World War II.

The final resting place of soldiers' loyal canine companions.

How this Pine Barrens hill got its name is uncertain, but on a good day the view from the fire tower is crystal clear.

This Great Depression-era creation was once known as the strangest house in the world.

This little-known collection holds everything from "Dracula" notes, to the manuscript of "Ulysses," to the forged works of Shakespeare.

Monty Python fans will recognize this abandoned mine as the Cave of the Killer Rabbit of Caerbannog.

It is said the legendary wizard once lived in this sea cave beneath Tintagel Castle.

A famous burial ground with a history both grim and literary.