This Industrial Age architectural and engineering gem helps visitors and residents alike traverse Lisbon, “The City of Seven Hills.”

This once-forgotten oasis in the middle of Lisbon was first created over a century ago quite by accident.

One man's remarkable private collection of art from around the world.

An exquisite collection of fairytale conveyances that puts most car museums to shame.

Located in the thermoelectric factory that once powered the entire city, this Portuguese museum is shockingly fascinating.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

The world's oldest bookshop still in operation.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

Berlin's old airport.

Home to 10,000 medical specimens including the remains of Rudolf Virchow's extensive collection of pathological specimens.

Berlin's beloved bear is immortalized at the Museum für Naturkunde.

Berlin's natural history museum houses the world's largest mounted dinosaur and the late beloved polar bear Knut.

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

A narrow passage next to a cafe leads to a courtyard exploding with murals, tags, and paste-ups.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

Legacy of the earthquake that nearly wiped Lisbon off the face of the Earth.

The most visited, and possibly most controversial, museum in Germany.

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

One of downtown Berlin's last reminders of its Communist past.

Where once there was a train station bathroom, there is now this German burger joint.