Hidden behind a wall for decades, this masonic lodge was only rediscovered during renovations.

A collection of comics, graphic novels, animation and caricatures devoted to exploring this often overlooked art form.

The sixth of London's "Magnificent Seven" cemeteries, and a source of unlikely inspiration to Beatrix Potter.

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

A cluttered and astounding collection of antiquities and curiosities.

The remains of Crystal Palace Great Exhibition of 1851.

London's smallest police station is barely the size of a phone booth.

The final resting place to 300 Victorian-era pets hides inside the city park.

Hear the quietest sound from across the dome.

Catacombs turned marketplace.

Eighty million natural history specimens call this gargantuan museum home.

Several plaster noses are hidden in plain sight around London's Soho neighborhood.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

The only university zoological museum in London houses extinct animals, bizarre natural history specimens, and a Micrarium of microscopic creatures.

Banksy gives themself artistic license with this piece of London street art.

Hidden beneath the streets of London is a secret subway that only carried mail.

The 18th-century home was disassembled into 253 cases and brought all the way from the other side of the world.

A whimsical menagerie of creatures carved into a 300-year-old tree trunk.

This historic Melbourne bullet factory is fully encased in a massive glass and steel cone.

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

Model Trains and Much More in Hamburg.

Böttcherstraße's bells, extolling Nordic virtues and the great conquerors of the world.

The only microgravity tower in Europe can produce nine seconds of weightlessness.

Eight naturally mummified bodies in glass coffins are housed in an underground crypt.