Finland's oldest astronomical observatory once played a crucial role in seafaring and timekeeping.

3,000 market stands in five former Zeppelin hangars.

The Brutalist building harbors an unusual inverted dome that swoops down over its central sacred room.

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

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

A historic scientific breakthrough that crosses nine borders.

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

An abandoned textile factory on the "island of crows" was home to Estonia's first workers' strike.

The oldest church in the Estonian capital is home to over 100 fantastical cemetery coats-of-arms.

Estonia's largest creative city is a vibrant bohemian hub located within a former industrial complex.

A secluded art gallery hidden within the cellars beneath Tallinn’s medieval monastery.

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

A menacing statue of this mythical creature can be seen at the legendary site of the monster's lair.

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

A 246-foot-high revolving restaurant rises unexpectedly from a forested Finnish hilltop.

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

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

Special benches that play Chopin's music are scattered throughout his native city.

A trough of 700 strange bronze faces runs through a narrow alley in Ljubljana's old town.

This demon atop the Notre-Dame de Paris looks utterly bored.

A labyrinth hides in plain sight at each of the city's 270 Tube stations.

The Polish capital has had a deep connection to its guardian mermaid for almost a millennium now.

It's a mystery why these remains were found with no traces of their bodies in sight.

An artificial date palm stands as a memorial to Warsaw's Jewish community.