This small chapel is built of human bones and decorated with a golden skeleton.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

One of Europe's largest supercomputers is housed inside of a disused chapel.

Mysterious Spanish catacombs of unknown origins.

A Spanish forest is filled with mysterious stone carvings.

This hill made entirely of ancient Roman jars was simply a garbage dump to the people of the time.

This walkway is so narrow it needs its own light to stop pedestrian traffic jams.

What looks like a crashed Zeppelin is actually a bright, airy reading room perched atop a modern museum.

A memorial museum to the political prisoners who were held at Sighet Prison, once one of the most feared places in Romania.

Hundreds of boat-shaped headstones fill this graveyard as part of a centuries-old custom with mysterious origins.

A spooky spot along the road where things mysteriously seem to move uphill by themselves.

Long abandoned underground complex to keep royals safe from a nuclear war that never came.

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

A hidden tunnel leads to a medieval queen's shrine buried beneath a parking lot.

Accessible only at low tide, the deserted island is dotted with World War II ruins.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

Winding paths and ramshackle mausoleums in the oldest "park cemetery" in London.

A kaleidoscopic warehouse-maze of handmade neon signs.

Rare wooden escalators lead deep down into an otherwise staggeringly monotonous tiled tunnel.

The oldest garden in Prague, once part of an medieval orchard.

A sculpture of the iconic East German car on four legs is a tribute to those who traveled to Prague seeking asylum.

Steadily reminding Czechia of its past.