The entrance to this Frankfurt subway station looks like an old tram car crashed into the concrete sidewalk.

From Nazi chemicals to the CIA, this architectural marvel has played a fascinating role in German history.

Fantastic views and thousands of love locks.

The largest bell in the world has been swinging high above a Cologne cathedral for almost a century.

The bones of the Biblical Magi traveled to Constantinople and Milan before landing in their current home inside an elaborate golden reliquary in the Cologne Cathedral.

Thousands of tourists and residents in Cologne affix "love padlocks" on the Hohenzollernbrücke Bridge to symbolize their affections.

Thousands of flowers create enchanting pink tunnels over the city streets.

A pair of giant stone heads represent the ancient Roman saints beheaded here.

Once the most densely populated place in the world, this island is now a ghost town.

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