San Francisco's newly reopened hands-on science museum.

The deepest metro station in the world.

A reconstructed medieval gateway that was the magnificent entrance to the capital city dating back to 1037.

This derelict superstructure was a very important warning system for the Soviet military.

One of the most poignant ruins of the Chernobyl nuclear disaster, the local football team's stadium has been quickly reclaimed by nature.

This attraction was abandoned after the Chernobyl disaster.

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

This beautiful natural train tunnel is said to grant the wishes of visiting lovebirds.

A war-torn Olympic relic is being overtaken by graffiti and nature.

The haunting ruins of a military fortress turned astronomical observatory sit on a Sarajevo mountaintop.

This surreal memorial/cemetery is a necropolis of crumbling stonework and puzzle-shaped headstones.

The sad remains of a monument to martial arts legend and movie star Bruce Lee—in the middle of Balkans.

A former bank seized as a sniper vantage point during the Bosnian War is now a secret graffiti art gallery.

This abandoned airplane hanger is said to have once been a top secret launch facility.

A restaurant and observation deck built in a unique broadcasting antenna.

The "Prussian Versailles" that is as glorious today as when it was built.

Berlin's old airport.

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

This "floating railway" is one of the world's oldest monorail systems.

A fascinating insight into daily life in the Eastern Bloc.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

An abandoned NSA listening post on Berlin's "Devil's Mountain."

A field filled with carved medieval tombstones called stećak.