A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

A beautiful but toxic fountain of mercury.

A Jenga-style cylindrical tower of books that appears to go on forever.

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

A national collection of Communist-era musical posters.

A program of Communist glamour in post-Stalin Poland is preserved in this colorful museum.

From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

A marvel of technology a century ago, this disused power station now offers a lovely glimpse into the industrial design of the past.

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

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

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

An ultra-modern diversity park in Denmark has turned an entire city block electric pink.

This ghost town in Belgium will lose its street art when it ceases to exist.

This unassuming museum's slogan translates to “there is a limit of sadness, anxiety has no limits."

The ghost town left by the worst nuclear disaster of all time is being taken over by nature and urban explorers.

Sweden's first nuclear reactor, R1, can be visited 25 meters underground.

The internet as provided by a James Bond villain.

These crumbling Nazi artillery bunkers are now fair game for massive graffiti projects.

This abandoned Belgian fortress is purposefully being left to nature.

A UFO-shaped event building originally intended to be a science museum showcasing the future.

Cozy basement bar sports an inventory of over 2,000 beers.

Climb inside an iron crystal magnified 165 billion times its normal size.