The world's largest bicycle shelter can hold more than 12,500 two-wheelers.

This bell tower is the only one of its kind in the Netherlands and was a symbol of prestige.

Inside this metro station is a section of the city's former medieval fortification.

This bronze statue of Martin Luther King was placed in the park without permission.

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

An enormous Polaroid picture adds an artistic flair to Rotterdam.

This hotel was once home to a steamliner company and became the final rest stop for Europeans heading to the New World.

This colorfully-painted tunnel links two distinct parts of a historic neighborhood.

The ruins of a medieval castle that once belonged to one of the most powerful families in the Netherlands.

This massive mural by famed pop-artist Keith Haring was hidden for almost 30 years until its 2018 rediscovery.

A giant floating rubber duck-bunny painted with a different design every year.

This former hydraulic laboratory is now a woodland dotted with old engineering models.

Deep in the forest next to Augsburg are abandoned bunkers and bullet traps from the region's military past.

A surreal statue honoring Prague's favorite literary son.

This impressive collection of rare books on ancient mysticism inspired author Dan Brown.

This museum inside Amsterdam's largest cemetery explores how people deal with death.

These former Nazi anti-aircraft towers offer a singular view of the north of Berlin in the summer, and a sanctuary for bats in winter.

A museum in the building where Nazi Germany signed its surrender tells the story of World War II from the Soviet perspective.

This functional solar system model was inspired by the famous Eisinga Planetarium.

The elegant manor house where Kaiser Wilhelm II lived in exile after World War I.

An impressive array of unique homemade planetariums.

The last bastion of Roman presence north of the Alps looms over a German town.

An early 19th-century English style garden hidden in the Rotterdam cityscape.

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