From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

These caves secretly held national treasures during World War II.

This 15th-century island fortress later served as home to the executioners no one wanted to live near.

Where commuters walk through remnants of an ancient Greek necropolis.

This small 16th-century church in Athens is almost entirely surrounded by a modern building.

Legend says this sacred tree was a gift from goddess Athena.

Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

Monasteries on rock pillars, once accessible only by frayed ropes.

A castle from the Holy Roman Empire that hosts traveling youth... in its stables.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

This red light district plaza memorializes the Fab Four and their historic connection to the area.

Once the tallest building in the world, this abandoned church is now a monument to the destruction of WWII.

This Dresden church was purposely rebuilt Protestant after being demolished in World War II.

This saucy statue once caused outrage among locals.

An Orthodox church built by the Royal Family for the Russian community exiled to the French Riviera.

Sky ships, planes, and portraits left as unique tokens of hope and thankfulness.

These enormous, stern-faced statues greet visitors with lanterns, and sometimes costumes.

This insurance company building reminds customers that witches, bears, and gnomes are out there, best be insured.

The old observatory in Copenhagen has a spiral corridor used as a racetrack.

Climb to the top of its spiral spire for spectacular views of Copenhagen.