The ruins of a fairytale castle with a tumultuous history stand high atop the mountains.

A tiny chapel perched along a 14th-century bridge.

Kuwait City's uniquely designed water towers look straight out of a retro sci-fi cityscape.

A jumble of treasures in a small space, this old-fashioned local museum is full of surprises.

Stockholm's narrowest alley is barely over two feet wide.

An architectural oddity hides in plain sight on this iconic London bridge.

The world-record holder for the longest bridge stretching continuously over water.

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

Hundreds of people walk past this palm tree every day without spotting its secret.

Cavemen, elephants, and eagles greet passengers driving through the town's main intersection.

A set of medieval stained-glass windows tell the gruesome story of a Viking siege.

This communist behemoth is the heaviest building in the world and a legacy of a brutal regime.

An impressive armored bronze effigy marks the tomb of one of the medieval era's greatest warriors.

A statue of the legendary Celtic warrior queen who fought the Roman invaders stands in one of the cities she once destroyed.

An incredibly well-preserved piece of ninth-century Viking poop.

One of the earliest large-scale "hyper" roofs in the U.K. is now a derelict roadside attraction.

A tiny village in Wales claims the name of a noble medieval hound slain for a crime he didn't commit.

This historic observatory contains the world's oldest refracting lens telescope.

Come for the flowers, stay for the bats!

Though considered an eyesore by some, this boxy Brutalist high-rise plays a significant role in Sydney's past.

This street has over a half-dozen names, all at once.

It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

This nugget of paradise earned its name for obvious reasons.

Meant to be a lavish presidential home, the palace became a symbol of the fall of South Vietnam.