This doorless 20th-century elevator doesn't stop or slow down.

This artificial cave looks like something out of a fairytale.

An eerie, existential museum dedicated to the author of "The Metamorphosis."

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

Buried five stories underground, this Soviet bunker is packed with gas masks and Cold War paraphernalia.

This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

This Prague museum collects brutalist relics and memories from the country's former Soviet rule.

The first museum in the world devoted to sexual gadgetry.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

The hidden lair of an alchemist rediscovered in a 2002 flood.

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

A rare octagonal brick beacon on an isolated island in the Baltic.

A small island dotted with old, historic Finnish buildings.

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

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

This scale model of our solar system hid in plain sight for years before a physics team sought out all the planets.

The big toe of this towering monument to a Croatian national hero is worn from years of superstitious rubbing.

An eclectic art form practiced by untrained masters is celebrated at this museum in the heart of Zagreb's old Upper Town.

When Croatia became independent of Yugoslavia, the splintering governments left behind these concrete tunnels.

Formerly Yugoslavia's "forbidden island," this sleepy little city still holds the abandoned remains of military strongholds.

Once a state-of-the-art tuberculosis treatment spa, these ruins are now ruled by paintball players.

Where the lovelorn find a home for their sentimental keepsakes.

An ethereal glowing blue ocean cave in Croatia.

Physicist’s epitaph provides final confirmation to a career of turmoil.