This abandoned Belgian fortress is purposefully being left to nature.

Nicolas Schöffer's massive interactive sculpture was assembled in 1961 and brought back online in 2016.

This giant urban staircase was built to keep the city's brave fighting men from getting waylaid in the red light district.

A once-magnificent collegiate church is falling into ruin.

This monolithic slab of art metal crowns a German slag heap.

This massive steel pyramid can be entered by a set of jagged steps that let visitors stand in its heart.

WWII rocket launchpad in rural Germany and site of operation backfire.

Danish whalers once brought back whale bones to use as building materials in places where wood was scarce.

A section of destroyed vertical lift bridge stands alone in the Peene river.

Only 380 kV Powerline in Europe not directly interconnected to the European 380 kV Grid.

A steam powered train that runs on city streets.

Twisted trees shaped by coastal winds make this woodland look like something from a spooky story.

Hitler's bleak vision of relaxation still stands as a mostly abandoned 10,000-room resort complex.

A long spiraling walkway winds through the woods, and around a copper beech tree at the center.

This 1960's Soviet submarine in Peenemünde Harbor claims to be the largest submarine museum in the world.

The NASA scientists behind Apollo 11 started out developing Nazi weapons at this abandoned German rocket factory.

An elevator into the Baltic Sea.