An underground city of salt.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

The silly symbol for an underground protest group is now scattered around the city.

These medieval skyscrapers dominate the skyline of this small Tuscan town.

It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

The Swedish flag over this small naval fort signals that the nation is at peace.

An ancient Viking runestone hidden in plain view in Stockholm's old town.

This homeless brass fox tugs at your heartstrings from the foot of a Stockholm bridge.

It houses the remains of a 17th-century version of the Titanic.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

Italian cave with exceptional acoustics and an unsavory history.

The world's most active stratovolcano is almost always erupting.

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

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

From toys to kettles to scientific instruments, this German museum celebrates the beauty of 20th century design.

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

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

After the parade, students throw their beads on the tree hoping for good luck on exams.

The state's oldest continuously operating museum houses more than 5,000 Civil War artifacts.

Formerly known as National D-Day Museum, this collection commemorates the battles of Normandy and WWII.

A museum and shop on Bourbon Street located in the French Quarter.

The curiosities and wonders of pharmacy in a delightful historic building.

The only arched bridge made of stone on the entire Mississippi River.

A toweringly silly piece of modern art has been delighting locals since the 1980s.