The ruins of this Dutch castle sit atop a labyrinth of once-secret tunnels and passageways, dating back over 900 years.

Birthplace of the "Cat in the Cradle" and a cluster of iconic, original windmills that let the Dutch tame the seas.

The vast chamber inside this abandoned cooling tower looks like something out of a sci-fi dystopia.

The last Oostende trawler to fish off Iceland is now a museum.

Abandoned since 1998, this train station has become an oasis for urban explorers.

This old, abandoned hotel offers magnificent views.

This memorial museum chronicles the apocalyptic destruction of the First World War.

Nature is slowly overtaking this disused cemetery on the outskirts of Brussels.

A Cold War command center is hidden under an idyllic countryside.

The Belgian royal family's private depot now stands abandoned and forgotten alongside the tracks.

Descend into the tunnels to experience the life of a coal miner.

This sprawling Belgian fort was once thought of as impenetrable but now it is simply an abandoned relic.

The site where one of the most famous poems of World War I was composed is preserved to honor the legacy of the work.

In an area where the remnants of WWI are discovered on a regular basis this preserved frontline trench may be the most amazing.

A rare example of World War I trenches from the British front.

This abandoned Belgian fortress is purposefully being left to nature.

A magical and peaceful ruined Cistercian abbey in what is now southern Belgium.

This ghost town in Belgium will lose its street art when it ceases to exist.

This noble mash-up in eastern Luxembourg is part Medieval, part Renaissance, all castle.

Once the local rulers had gone these enchanting ruins housed common folk in an almost real life fairy tale.

This Luxembourg cave is covered in cryptic looking marks left by mining activity.

Two standing giants remain as a tribute to Luxembourg's metallurgical past.

The site of the first battle of World War II.

This fairytale medieval church in Poland originally spent centuries in Norway.