A fantastical 13th-century fortification sandwiched by a modern hotel in central Brussels.

Hiding the longest subterranean river known in the world.

This little patch of Europe remained neutral for more than a century because of a mine.

Located inside Hoge Veluwe National Park, this museum began as the private collection of a prominent female art collector.

Oldest World War 2-themed museum in Western Europe.

A rare cold-water geyser that bubbles to life every half hour.

The highest cold-water geyser in the world.

Legends surrounding this megalithic tomb range from giants to a dwarf named Trollid.

Possibly the oldest of Britain's ancient henges is also one of its most stark.

A red sandstone freestanding monolith rises out of the sea in northern Scotland.

An amusement park on the grounds of an unused nuclear power plant, with a swing ride inside the cooling tower.

This large open-air museum showcases the ordinary lives of the people of the Netherlands and pre-industrial crafts and practices.

Organisms normally seen under a microscope decorate this church.

The largest airborne operation in history was launched to capture this bridge.

This World War II-era bunker hides between medieval chapels in Nijmegen's city center.

This African beach is home to thousands of rare mainland penguins that are known for their annoying voice.

This road winds through the steep coastal cliffside offering spectacular views for those who brave the drive.

The Cape of Good Hope is not quite as low as you can go on the African continent, but it's still geographically significant.

This towering church is home to a world-famous organ and a treasure trove of medieval art.

Oldest Museum of the Netherlands is a true cabinet of curiosities.

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

The Netherlands' first car tunnel has an unusually rectangular shape.

These lights mark the area of Rotterdam that was bombed and burned in 1940.

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