One of the world's oldest continuously operating meteorological stations sits on a hill in Stockholm.

An abstract representation of weather in Sweden.

An 11th-century runestone decorates the halls of Terminal 2 of this Scandinavian travel hub.

A plaque marks the house in Stockholm where the French philosopher René Descartes lived up until his death.

This half-forgotten fortress was constructed by the Ottoman conqueror of Constantinople.

A gorgeous, Gaudí-esque stairway constructed in the city of Istanbul by a prominent Jewish family.

A marvel of Byzantine engineering under the streets of Istanbul.

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

Neon artworks light up this dark Edinburgh tunnel.

A monument to the man who almost killed Hitler.

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

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

A community museum celebrates Glasgow's mighty shipbuilding days.

This emblematic representation is said to bring the students good fortune.

Inscribed on the gate are the names of 29 figures from the University's first five centuries.

The former home of the world-famous Templeton Carpet Factory.

This two-legged horse statue celebrates a beloved cartoonist and his quirky characters.

Glasgow's memorial to the International Brigade volunteers from Great Britain who fought and died in the Spanish Civil War.

Inside this art museum resides one of Glasgow's most famous musical instruments.

The old tradition of drying laundry on poles in the public green is still guaranteed by Glasgow city law.

Displaced highlanders would take shelter from the wet Scottish climate under the large walled bridge at Glasgow Central Station.

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

A scattered trail of street art adds a pop of color to the city's stark structures.

Climb this overlooked gem's spiral staircase and you'll be rewarded with spectacular views of Glasgow.