Structure built from the skulls of vanquished foes.

The largest bell in the world has been swinging high above a Cologne cathedral for almost a century.

A poignant mural honors the heroic teenage non-conformists who took on the Nazis and paid the ultimate price.

How did a lighthouse wind up in the middle of this landlocked German city?

The final resting place for a wealthy Roman family, this tomb might be the best preserved of its kind outside Italy.

An elegant chandelier hangs over this ancient sewer chamber, now open for concerts and public tours.

A church filled with the bones of hundreds of virgins martyrs—or so they say.

This small condiment museum makes all manner of mustards with a 200-year-old mill.

The body of at least one victim of a construction accident was left behind in the collapsed pylon, buried under tons of concrete.

Below the altar in Saint-Willibrord Basilica rests the mortal remains of Luxembourg's patron saint.

In the heart of Luxembourg's "little Switzerland" weaves a breathtaking natural sandstone canyon with a mythological past.

This noble mash-up in eastern Luxembourg is part Medieval, part Renaissance, all castle.

This Luxembourg cave is covered in cryptic looking marks left by mining activity.

A marble Lucifer hides behind the pulpit of this Gothic cathedral.

The exhibition explores the Icelandic city's Viking Age history.

This oceanside Reykjavik spot is speckled with recycled sculptures and large stones.

Iceland's first pagan temple in 1,000 years is underway in Reykjavík.

Where royalty waits in the height of luxury.

One of Amsterdam's narrowest houses is located right across the canal from its widest.

This unusual elevator doesn’t stop or slow down.

An ancient passage filled with stalls selling used books, once frequented by Vincent Van Gogh.

This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

This historic Amsterdam bar used to accept sailor's monkeys as payment.

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.