Located more than 600 feet beneath sea level, this tunnel boasts the world's first undersea roundabout.

At night, this glittering musical tunnel draws skaters and photographers.

Now in ruins, this castle stood for centuries and saw a number of gruesome events.

Wooden pathways run through this rocky landscape, which legend says was created when a dwarven king pulled down his own castle to stop raiding giants.

World War II-era Nazi compound nestled in the Santa Monica hills.

A devasting 2020 fire left this historic seminary in ruins.

The ruins of a 19th-century corn mill are haunted by a malevolent cave-dwelling spirit.

A derelict bit of transportation infrastructure hidden in the woods.

The Brigadier General was so afraid of being buried alive that he had a buzzer installed in his mausoleum, just in case he woke up.

Reclaimed material from a convent destroyed by cannonfire was used to build parts of this 19th-century cemetery.

This old mining town, deep in the California desert, has a year-round population of one.

A miniature rainforest is growing inside of a Midtown Manhattan office building.