Berlin's old airport.

A 12th-century fortress containing some of Berlin's oldest buildings.

A unique Holocaust memorial tells the personal stories of the Jewish residents exiled from greater Berlin.

The prototype for all Nazi concentration camps.

No need to strap in for a "ride" on this walkable roller coaster.

Super-heavy Nazi architectural experiment.

A small but immensely extravagant palace built by the "Night King."

"The most colorful grottoes of the world.

Soaring over 6,000 feet in the Bavarian Alps, this beer garden was once Hitler's 50th birthday present.

The site of the famous Nazi book burning campaign of 1933 remembers its "Night of Shame".

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

The 1936 Summer Olympics site is a crumbling remnant of sportsmanship and a history its host country would like to forget.

A striking 12th-century-style castle built on the edge of a cliff.

Berlin's natural history museum houses the world's largest mounted dinosaur and the late beloved polar bear Knut.

This Berlin island is home to a flock of free-roaming peacocks, as well as a historic ivory folly.

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

The most visited, and possibly most controversial, museum in Germany.

Ruins of a German Castle on top of a towering stone pillar.

The birthplace of an eccentric alchemist and possible inspiration for the fictional reanimator of monsters.

A tour of underground Berlin takes you through WWII air raid shelters and tunnels used to smuggle people out of East Germany.

The fairy tale castle of the "fairy-tale king."

Once the tallest building in the world and the site of "the highest dinner ever held in New York" this building now holds the most expensive penthouse in the city.

A three-story copper skybridge connects two Manhattan buildings with Art Deco luxury.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.