Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

Countless grotesque faces stare out from this eerie Prague art wall.

The most visited, and possibly most controversial, museum in Germany.

The walls of Germany's Parliament still show the scars of the Red Army takeover in World War II.

Tiny memorials honor individual victims of the Holocaust.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

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

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

The unbelievably opulent home built for an infamous newspaperman.

This stunning sea creature-shaped home blends into the landscape like a fantasy villa.

The world's first clock to use set theory as a measure of time required the invention of a new light bulb just to maintain its obtuse measurements.

London's old-school healing garden.

A clock designed to run with perfect accuracy for 10,000 years.

Scattered throughout London are ancient remnants of the city's former bounding wall.

One of the world's largest collections of pathological specimens.

A Victorian natural history and ethnographic museum with wonderful turn-of-the-century, science-book-esque evolution displays.

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

The largest of London's subterranean rivers and once a mad, bad center of London life.

The curios of pharmacist and collector Henry Wellcome.

A student driver's nightmare.

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

A hands-off space for graffiti artists to hone and display their skills.

A 300-year-old tea shop that brought tea to the English people, not to mention the Queen herself.