This tri-part waterfall is a little bit of fairytale beauty in the heart of Luxembourg's Little Switzerland.

The mile-long pier stretches from a ruined fortress out into the Baltic.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

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

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

The video game-themed street art first popped up in the French city.

This life-size replica of the Statue of Liberty's flame is also a tribute to Princess Diana by default.

The curious underground history of keeping Paris clean.

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

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

The smaller of the three towers of San Marino is a former prison inaccessible from the ground level.

High in the clouds of San Marino sits an ancient tower with some curious prisoner graffiti.

France's most famous cemetery, with some of its most curious tombs.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

Architectural monsters are devouring this palace's every door and window.

The fairy tale castle of the "fairy-tale king."

Subterranean place of worship in Indonesia.

This massive complex is made up of hundreds of smaller temples that date back to the ninth century.