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 best place in the world to buy tinned fish.

Elaborate tile work in this railway station tells the story of Portugal.

This trio of Dominican cave lakes comprise a colorful biosphere of natural life.

One of the largest underground systems runs under Canada's largest urban center.

A Dutch clog company in the town of Zaandam loves the wooden shoes so much it made a museum for them.

The Rozenberg wind wall in South Holland makes for smooth sailing through the Calandbrug canal.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

A museum that cashes in on its infamous little people while teaching you a thing or two about the Irish fey.

Ireland's most remarkable collection of these curious cone-shaped houses is worth the buzz.

The celebrated eyesore created by starry-eyed sweethearts.

The prototype for all Nazi concentration camps.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

A copy of the famous statue can be found in this Florence piazza, along with one of the most breathtaking views of the city below.

2300-year-old Roman road connecting the empire.

The world's largest wooden structure.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Museum dedicated to the terror regimes of Hungary.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

This splendid tomb may look fantastic, but there's nothing in it...

This one-time health resort was used by aristocrats around the world.

The 400-year-old remains of the samurai invasion of Korea.

Peace Park and the Atomic Bomb Dome.