An acoustic anomaly with a mysterious cause.

In a 345-million-year-old cave that's 200 feet underground, dinner awaits.

This painted Lego bridge is the product of over a century of locomotive history.

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.

Striking occult iconography on a medieval German church.

Remnants of an exploded schooner and wrecked submarines form a breakwater.

It's always summer at the beach inside this former airship hangar.

These blingy, baubled skeletons lie in glass boxes inside a baroque Bavarian church.

An elevator into the Baltic Sea.

Floating swimming pool within a moored vessel.

Blitzkrieg bop your way through Berlin's Ramones Museum.

What started as a tongue-in-cheek shrine is now a full-blown museum celebrating "The Hoff" and his longtime love affair with Berlin.

The patron saint of spinsters grasps a container of dried blood.

A stairway to heaven, or to nowhere at all.

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

The largest free-standing aquarium in the world resides in a hotel lobby in Berlin.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.

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

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

An eerie, derelict amusement park in Berlin.

This recently restored crypt was once plagued by liquefying coffins and exploding caskets.

Medical history with an amazing, if frighting, collection of wax diseases on display.

Because sometimes the most efficient route from A to B isn't a straight line.

Giant scissors seemingly stabbed into the side of a hair salon leave no question about the vocation of the owners.