The world's first clock to use set theory as a measure of time required the invention of a new light bulb just to maintain its obtuse measurements.

Retirement home for giant obsolete machines.

This museum tells the story of lake dwellers from 4000 BC to 850 BC, replete with stilt houses and goats.

Berlin's old airport.

This historic stone bridge has an entire neighborhood clinging to its sides.

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

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

A sprawling Baroque park with 300-year-old hydro-pneumatic waterworks.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

Rock-hewn monastery complex with hundreds of cave structures tucked away into the mountainside.

At first glance, little checkered structures on the hillside look like they house the living, not the dead.

A church of bones, decorated with 40,000 human skeletons.

This modern French ossuary contains the jumbled bones of 130,000 WWI soldiers.

A colossal sculptural lion built by the same man who designed the Statue of Liberty.

This spooky statue sits outside a famous Prague theater.

The slender brass strip in Prague's Old Town Square was used to tell time from 1652 to 1918.

Monument to a suicide protesting the Soviet invasion.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

Macabre astrological automaton clock dating to the late 1400s.

This excellent museum recreates the boom days of the herring rush in the "Atlantic Klondike."

In Northeastern Iceland lies something of an oxymoron: a steaming desert.

Iceland's tribute to its thankless civil servants.