At one of Berlin’s oldest churches, visitors can place mosaic tiles to help restore a medieval mural.

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

Tiny memorials honor individual victims of the Holocaust.

A museum in the building where Nazi Germany signed its surrender tells the story of World War II from the Soviet perspective.

The last remnants of a massive medieval wall that once encompassed the city of Berlin.

The final resting place of many of Germany's most famous communists.

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

The walls of Germany's Parliament still show the scars of the Red Army takeover in World War II.

This conical hill was built as a testing ground for an engineer known as the Glider King.

Super-heavy Nazi architectural experiment.

What started as a tongue-in-cheek shrine is now a full-blown museum celebrating "The Hoff" and his longtime love affair with Berlin.

A fascinating insight into daily life in the Eastern Bloc.

A wunderkammer of mysterious objects and stories.

A museum dedicated to the history of a terrifying secret police is now held in their former headquarters.

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

An unusual stroll through gentlemen's erotica demonstrates that pornography is timeless.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

A model solar system adds a celestial touch to this suburban park.

A rare set of strings by famed instrument maker Antonio Stradivarius is on display in the Royal Palace.

Occupied for six centuries by Franciscan Order nuns, this monastery is an amazing ode to Catalán Gothic architecture.

A cemetery in Barcelona's Poblenou district is home to this touching funerary statue, which depicts death in the form of a winged skeleton.

One of Antoni Gaudí's least-visited works, an homage to Catalan patrimony that mixes neo-Gothic with Modernista forms.

This cemetery features modernist statues as strange as its name.