An old department store turned Nazi prison turned artist commune.

Remains of a huge radio tower.

A statue of Vladimir Illyich Lenin guards this abandoned building in the "Forbidden City."

Hidden in the forest are the crumbling, graffiti-covered remains of the factory where most of Germany's explosives were produced during World War II.

Several of these strange cone-shaped bunkers can still be seen around the former Nazi headquarters.

This former Soviet military base has over 10 original aircraft and an enormous amount of memorabilia on display.

These abandoned Cold War-era bunkers are now a designated refuge for endangered bat species.

Obscured within a ring of trees, this abandoned World War II relic hides on a German hillside.

A top-secret bunker now turned museum, is an eerie look at what life would have looked like in the event of nuclear war.

A preserved college lock-up that recalls a clubhouse approach to discipline.

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

This East German military command bunker was ready for World War III.

There are two dozen tanks just sitting in an open field in Lower Saxony.

Solar observatory doubles as a daring display of Expressionist architecture, much to Einstein's chagrin.

A preserved Nazi labor camp now has a Holocaust museum on site and memorials to the thousands that died while imprisoned at the camp.

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

The site of a concentration camp where inmates were made to take part in one of the largest counterfeiting operations in history is now hauntingly empty.

Thousands of flowers create enchanting pink tunnels over the city streets.

A former ironworks that was the first UNESCO industrial site.

Retirement home for giant obsolete machines.

The oldest Jewish cemetery in Europe survived Hitler's Germany.

These former Nazi anti-aircraft towers offer a singular view of the north of Berlin in the summer, and a sanctuary for bats in winter.

When German-Iraqi relations broke down, this embassy was vacated post haste.

An eerie, derelict amusement park in Berlin.