The largest underground church in Europe.

An immersive projection art installation uses sound, scale, and light to take visitors inside classic works of art.

A 14th century bridge built as a fortress, where the devil lurks on one of its towers.

A cave dwelling that was started by the Celts, expanded by monks, and finished by knights.

One of the greatest maze designer’s greatest mazes.

Sacked by Vikings, blessed by William the Conqueror, dealt a fatal blow during the French Revolution—these ruins have seen it all.

This French ghost town from World War II has been left as a memorial to German atrocities during World War II.

Exquisite wall sculptures carved in secret by an early quarryman in an obscure corner of the Paris Catacombs.

Go inside to really appreciate this 500-year-old technological masterpiece.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

The plague quarantine island home to the alleged "Vampire of Venice."

A sinister pyramid in the Frari contains the heart of the famous neoclassical sculptor.

Venice's "Island of the Mad."

As can be expected from a centuries old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

This abandoned Belgian fortress is purposefully being left to nature.

A statue of the second-tallest Dutchman in history.

Strange secondhand shop showcasing taxidermy and oddies

A miniature city, once ruled by the Queen of the Netherlands.

Some believe that this ancient mural depicts technology far ahead of its time, but in reality it's nothing quite out of place.

The deadliest diving spot in the world is also a stunning geological marvel.

A massive work of modern art that appears to be a crop circle in the middle of the desert.

In Egypt's expanding metro area, many of the neighbors are dead.

A 12th-century fortress containing some of Berlin's oldest buildings.

Art and a pun, all in one.