A plaque hidden in the law faculty at Leiden University honors the first scientist to make liquid helium.

Sweden's first electric elevator remains hidden within a fortress-like building.

A market built atop boats is one of the few floating holiday markets in Europe.

Stockholm's deepest subway station is also a stunning ecological wonder.

Now a museum, this building was once a 14th-century monastery and the place where the founder of the Dutch nation lived and was assassinated.

In the days before house numbers, these colorful signs held clues about various buildings' purposes.

This gem from the industrial age helps visitors and residents alike traverse hilly Stockholm.

A miniature model of the iconic Stockholm department store.

A delightful but little-known public observatory and planetarium in Munich.

This red London phone booth once stood in front of Buckingham Palace and was used by the queen.

A fearsome dragon clings to a corner of Munich's city hall.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

The footprint of a frustrated devil in Munich's Cathedral.

The patron saint of spinsters grasps a container of dried blood.

These crevices cut into the mountains collect the island’s main source of precious freshwater.

A rocky face gazes out over an enormous volcanic crater.

A 1:42 scale model of the world's second largest lensed telescope.

A detailed 1:32 scale model of Scandinavia's largest telescope.

The largest salt farm in the Canary Islands is located at the foot of an active volcano.

These wooden balconies that are both decorative and functional.

The mysterious large white cross visible from the runway is a memorial to a massacre during Spanish Civil War.

People have been placing babies on these lilies for photoshoots since the Victorian era.

The world's largest private telescope collection hides in a secret wing of a Dutch auto museum.

In the Netherlands, one of the world's largest private car collections can be found.