The largest free-standing aquarium in the world resides in a hotel lobby in Berlin.

An empty bookshelf commemorates the books which were lost during the infamous event

A poignant memorial that traces two hundred years of German history.

Check the time in 145 countries at once with this East German relic.

Dedicated to the European Sinti and Roma peoples murdered during the Holocaust.

This watchtower once presided over the Berlin Wall.

A towering monument to war, located on a beautifully peaceful hill.

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

An abandoned NSA listening post on Berlin's "Devil's Mountain."

Along the banks of the Teltow Canal in southwestern Berlin stands one of the city’s most controversial buildings, a hulking Brutalist laboratory that looks more like a warship than a research facility.

Ever-changing museum dedicated to graffiti and contemporary street art.

In the middle of a Vienna square, Roman ruins dating back some 2,000 years are on display.

Along the edge of this fountain are 365 smaller fountains that represent the days of the year.

A magnificent collection of imperial armor and weaponry.

Giant WWII fortresses that fired 8,000 rounds a minute, now home to thousands of pigeons.

Handsomely crafted representations of our round planet.

A spherical "micro-nation" in the heart of Vienna.

Dine amidst exotic plants at this former royal greenhouse.

The world’s oldest military museum has remained largely unchanged since the last days of the Austro-Hungarian Empire.

A sinister pyramid in the Frari contains the heart of the famous neoclassical sculptor.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

Go inside to really appreciate this 500-year-old technological masterpiece.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

A quiet patch of astroturf laid out between a building that seems to be splitting in half.