Artfully arranged bones of 5,800 Austrians.

A unique hotel for the artistic soul.

This series of underground chambers contains Europe's largest subterranean lake that is slowly drained each day.

This cubist Vienna church building looks like some sort of alien stonehenge.

The topiary maze at the Habsburg hunting lodge.

A neo-Gothic church built to thank God for saving the Emperor of Austria from an assassination.

Giant WWII fortresses that fired 8,000 rounds a minute, now home to thousands of pigeons.

An exquisite Baroque church in Vienna's old town.

The solemn exterior conceals an opulent interior of this 17th century church.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

This former insane asylum now holds a pathological anatomy museum.

Bursting forth from a historic German neighborhood, these day-glo palaces are now a bright fixture in the town.

When the rain falls, this drain system turns into a musical instrument.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

The industrial monstrosity known as Bagger 258 is a colossal mining machine built in the DDR - but now left for dead in a German field.

The architect of this fanciful complex called it an "oasis for humanity and nature in a sea of rational houses."

Retirement home for giant obsolete machines.

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

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.

Terrifying derelict military hospital once housed a recuperating Hitler.

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

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

A narrow passage next to a cafe leads to a courtyard exploding with murals, tags, and paste-ups.

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