Ancient man-made caves underneath small town Belgium.

Theme park featuring miniature replicas of European monuments.

Sculpture designed by Turkish artist and professor Mehmet Ali Uysal.

This abandoned Belgian fortress is purposefully being left to nature.

Hiding the longest subterranean river known in the world.

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

Medical history with an amazing, if frighting, collection of wax diseases on display.

Lavish royal estate punctuated with heated greenhouses.

Underneath a chalk hill in France lies what Hitler hoped would be the underground launching base for a devastating new weapon.

These crumbling Nazi artillery bunkers are now fair game for massive graffiti projects.