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

The barrel-made lookout from Shackleton's final ship is tucked away in the crypt of one of London's oldest churches.

Tucked away in the Tower of London is the weapon once used to execute high-profile prisoners.

These morbid carvings remind churchgoers of the inevitability of death.

These official units of measurement—including chains and perches—lie hidden beneath tourists' feet in a popular London hub.

This London plaque marks the spot where David Bowie's famous alien made his debut.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

Thanks to modern navigational tools we now know that the true prime meridian runs through a park next door.

A unique collection of Soviet military artifacts lies hidden away in a disused train, in the unrecognized Eastern European republic of Transnistria.

A forgotten remnant of the Soviet Union, Transnistria is an unrecognized country hidden behind a heavily militarized border between Moldova and Ukraine.

The last planned Soviet city was built for the former residents of Pripyat after the Chernobyl disaster.

A former top secret nuclear fallout shelter now operates like a hotel stuck in the Cold War.

The world's greatest slide descends 18 stories from this looping mountaintop viewing platform.

This former quarry is now a picturesque gorge that hides a sunken lake.

Europe's largest natural bridge has a 19th century royal chateau built into its side.

Europe's second largest ossuary wasn't discovered until 2001.

Street artists transformed an abandoned air vent into the beloved Star Wars robot.

Buried five stories underground, this Soviet bunker is packed with gas masks and Cold War paraphernalia.

The deepest sinkhole in Central Europe comes with a grisly tale and an unusual nickname: “The Stepmother Abyss.”

A bust of the first president welcomes visitors to the only town in America called George, Washington.

This inanimate goat created by the "welding nun" has been helping to clean up the city of Spokane for more than 40 years.

This oddity shop contains everything from antique tools to a human skeleton.

A giant milk bottle from the 1930s beckons drivers to this diner.

This Cold War missile launch site has been abandoned for 40 years.