This Nazi ruin was the site where Hitler was almost blown up by a suitcase bomb.

The history of radiation is on safe display at the foot of a radiation science laboratory.

Austria's very first and only nuclear power station was completed but never used.

The small cliffside monastery known as the Tiger's Nest is said to be the meditation site of an 8th-century Buddhist master.

Venice's "Island of the Mad."

The art museum is decorated with creatively remodeled pre-Nazi swastikas.

A unique, modernist church tower that appears to float above the ground.

Denmark's famous pseudo-hill.

An abandoned lighthouse awaits its destiny: being buried under shifting sand.

Bored potato-guarding Nazis etched their thoughts onto a brick storage building in Copenhagen's Meatpacking District.

The gilded, masterful astronomical clock will calculate time, dates, and planetary positions for thousands of years to come.

A natural wonder in south Denmark.

This secret collection of the strange and occult was rediscovered in a forgotten room of an old house.

A walkable map of the world, made from soil and stone by one man.

This large, circular tomb is the final resting place of the first emperor of Rome.

This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

Like something out of a bad acid trip, this Ukraine hallway has been covered in hallucinatory phantasmagoria.

One of the largest museums in Ukraine remembers the story of the German-Soviet War in iconic, brutalist style.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

An eerie, derelict amusement park in Berlin.

This exquisite, alienesque piece of Soviet architecture is being threatened by modern shopping malls.

This unlicensed collection of fast-food memorabilia sits on the site of the first ever McDonald's restaurant.

Inside this McDonald's you can dine on your Big Mac and fries next to a 2,500-year-old Roman wall.

This 18th-century fort surrounded by a moat was used to store gun powder and ammunition, and now sits in the middle of a large part in Dublin.