The secret cells in the basement of the KGB's Estonian "Grey House" have been preserved as a grim Cold War museum.

First point in the Struve Geodetic Arc, a 19th century undertaking to measure the Earth's size and shape.

The labyrinthine home of the National Archives of Estonia is an experimental blend of architecture, art, and history.

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

This endearingly discomfited urinating statue commemorates the sneaky pees had by us all.

Architecturally stunning library serves as the hub of Finnish scholarly life and culture.

A subterranean house of worship carved right out of the bedrock.

An abstract monument to a symphonic composer.

No matter how many times this community-run sauna gets destroyed, it always rises from the ashes.

Every summer, an open-air swimming pool appears at the base of a Finnish city's beloved winter attraction.

The bears of Bern have been a city highlight for over 500 years.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

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

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

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

A museum dedicated to a secret military hospital hidden beneath a castle in Budapest.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

This Budapest bar allows drinkers to leave their mark on the walls, floor, and even ceiling.

A random tree outside a Budapest hotel has become a DIY shrine to the late singer.

Thousands of slain Soviet soldiers are buried within the shadow of this enormous obelisk.

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

This Slovakian statue of an emerging sewer worker might just be a bronze peeping tom.

Go surfing on this urban wave, "hacked" by local surfers.