A massive explosion that leveled hundreds of buildings in the city of Leiden is remembered by a waterside plaque.

It's forbidden to dig within this ancient Roman fort hidden beneath a playground.

This 11th-century castle sits so low you can't see it behind the surrounding buildings.

Graffiti covers the walls of a room where university students through the centuries have waited nervously to defend their theses.

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

The works of poetry's biggest names grace the walls of the city of Leiden, all carefully painted by hand.

Science meets wall art to highlight the beauty of famous mathematical equations.

A former plague hospital turned medical museum.

Devious political maneuvering and four ancient, working telescopes are central to the world's second-oldest observatory.

A 'living museum' in Leiden, the oldest of its kind in the Netherlands.

Rich with fauna and flora, nature-lovers can walk across the sea at this UNESCO World Heritage spot.

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

Visitors can explore the role of mysticism throughout the ages inside this interactive museum of magic.

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

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

These slanted cubic abodes are a creative if odd solution to a zoning pickle.

Old ships and machinery fill a historic harbor in the city that's home to Europe's largest port.

Rotterdammers' dirty minds gave this santa a dirty nickname and cursed it to a life of wandering.

This charming pup is meant to celebrate the youth and stubbornness of the city's students.

A modern reimagining of a medieval city gate.

Built by crowdsourcing, this wooden foot bridge saved a part of Rotterdam that was languishing in wait of city funding.

A dramatic art installation features a BMW flying out of a building in Rotterdam.

Four giant movable street lights decorate this modern Rotterdam square.