The iconic boulevard is the perfect place to catch sight of a bicycling skeleton, a levitating Satan, or a chef with his head stuck in a pizza.

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

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

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

The site of the first medieval crusade that pitted Christians against Christians.

French commune at the heart of conspiracies.

The world's tallest bridge is also possibly the most elegant.

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

Historic medieval fortified city in southwest France.

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

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

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

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

The medieval woodcut-style artwork chronicles life in medieval London.

This intriguing Bronze Age artifact spent centuries hidden within a Welsh faerie hill.

This bewitching Babylonian goddess haunts a hallway of the British Museum.

These mysterious Viking chess pieces spent centuries hidden on a remote Scottish island.

The Tudor-style cottage in the middle of the square is not quite what it seems.

"We gonna rock down to Electric Avenue, and then we'll take it higher..."

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

Mary Kelly was last seen here before she was murdered by Jack the Ripper.

The largest of London's subterranean rivers and once a mad, bad center of London life.

Hear the quietest sound from across the dome.