This foreboding medieval castle was twice besieged by barons rebelling against the English king.

This medieval church tower has maintained its clockworks since the 16th century.

Rare wooden escalators lead deep down into an otherwise staggeringly monotonous tiled tunnel.

Most prolific publishing house in the 1600s open to the public.

An unassuming London park is actually a pilgrimage site for modern clowns.

A measuring mishap led to these artificial stone ladies losing their stomachs.

The "lost friend” is the most famous of the six moai statues that were removed from Easter Island.

On October 17, 1814, a 15-ft. wave of beer ran rampant through the streets of London.

The cedar tree in Highgate Cemetery earned its title by accident.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

Repository for more than 22 million pickled specimens.

This marine reptile was discovered by one of the 19th century's greatest fossil hunters.

The home studio one of Britain's first independent record producers is also the site of a murder-suicide.

The world's widest single drop waterfall, and the two men who legend says went over its edge in a boat.

This macabre masterpiece of a mural is one of Francisco Goya's "Black Paintings."

Long tunnels run under the ancient chariot racing circuit to the tower.

According to the Guanches, the aboriginal people of the Canary Islands, the king of evil lives inside this volcano.

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.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

Stunning Roman aqueduct used for 1900 years and still standing.

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

An ancient Egyptian temple in the middle of Madrid, Spain.

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