The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

An underground city of salt.

This functioning parish church is also the site of many concert performances due to its wonderful acoustics.

These historic defenses ensured the city within would survive hundreds of years of occupations, sieges, and invasions.

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

Museum dedicated to the terror regimes of Hungary.

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.

Metro station with a claim to rock n' roll fame.

Cold war icon and onetime "hole" in the iron curtain.

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

Berlin's old airport.

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

A fascinating insight into daily life in the Eastern Bloc.

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

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

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

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

The prototype for all Nazi concentration camps.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

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

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

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

The celebrated eyesore created by starry-eyed sweethearts.