A small island dotted with old, historic Finnish buildings.

An abstract monument to a symphonic composer.

This irregularly shaped sea fortress has defended not one but three different sovereign states.

It houses the remains of a 17th-century version of the Titanic.

An ancient octagonal weather station named for the eight Greek gods of wind.

This legendary city has been a tourist attraction for centuries.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

Monasteries on rock pillars, once accessible only by frayed ropes.

The "dragon babies" of southeastern Europe.

A whimsical bridge adorned with decorative dragons.

A miniature train-ride through Slovenia's largest cave system.

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

This massive subterranean fissure is known as the "underground Grand Canyon."

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

This Roman underground canal was the longest tunnel ever built until the late 19th-century.

The rotting skeleton of a shoreside fun fair that was destroyed by fire and storms still haunts the Brighton ocean view.

Regency-era excess on the English Coast.

The statue of John Harvard isn't actually John Harvard—or even, technically, the founder of the school.

Bouncing, delightful, mechanical art at the MIT Museum.

An extraordinary library and archive dedicated to the history of the Arctic and Antarctic poles.

This massive statue is the personification of Bavaria and the first colossal statue of the modern period composed of bronze.

This beautiful 19th-century temple stands atop the ruins of its predecessor.

This magnificent museum claims to house the cranium of a disciple and the skull of a pope.

King Ludwig I's collection of beautiful women.