Its frescoes depict the likeness of Marshal Tito, Karl Marx, and Friedrich Engels burning in hell.

This virtually windowless mass of smooth concrete is the only Catholic church in the city.

This top-secret nuclear bunker hidden in a Bosnian mountain has been converted to a modern art exhibition space.

The haunting ruins of a military fortress turned astronomical observatory sit on a Sarajevo mountaintop.

The remains of an ancient Roman city are hidden underneath Bologna's beautiful public library.

A striking memorial recalls thousands of Bolognese men and women killed fighting fascists in World War II.

Time has been frozen at this station since the bombing in 1980—or so it was believed.

The wreckage of a tragic plane crash is on display at this museum devoted to a famous Italian conspiracy.

The intricate geometry inside this Baroque-style dome was designed to create "terror of the human soul."

An abandoned shopping gallery built during Fascist Italy tucked in the center of Palermo.

The unexpectedly beloved remnants of a controversial thermal power plant.

Built by crowdsourcing, this wooden foot bridge saved a part of Rotterdam that was languishing in wait of city funding.

A small square plaque marks a failed assassination attempt that could have changed history.

The prototype for all Nazi concentration camps.

Every hour the doors open to reenact the legend of the heroic mayor who saved his town by drinking a gallon of wine.

This natural hill rose another 130 feet from the debris and rubble added after World War II.

This old wooden funicular railway leads to a cemetery in the forest.

Twisted buildings adorn the banks of the Rhine river.

This futuristic German television spire is actually the world's largest digital clock.

This concrete church spent a period of its history as a World War II bunker.

This former Nazi castle was built as a school to train what would have been the future of the Third Reich.

An icon of the Battle of Britain is frozen in flight in a grand Victorian museum.

This historic pub has maintained much of its 1906 decor, including a small sequestered room for women, where orders were slipped through a tiny window.

The sweet story of how American cargo planes became known as "Candy Bombers" during the Berlin Blockade.