Hidden in the forest are the remains of a former World War II chemical plant.

This unique structure allowed boats to bypass underwater mine barriers in the channel to enter the harbor.

In the city forest of Augsburg are oval, artificial ponds formed from a World War II bombing campaign.

Next to the well-known retaining weir "Hochablass" is the former raft port for the city of Augsburg.

This fountain tucked away in a park is the focal point of the only "Green Basilica" in Germany.

The world's first jet-powered aircraft were assembled by the Germans in this secret factory in the forest during WWII.

Legend says this sculpture commemorates a brave baker who rescued the city in the Thirty Years' War.

Hidden in the forest are the crumbling, graffiti-covered remains of the factory where most of Germany's explosives were produced during World War II.

What appears to be an ordinary bridge is actually a rare aqueduct.

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

Originally slated to become a luxurious resort, this structure is now a graffiti haunt reclaimed by nature.

The abandoned club hides in the hills of Ibiza.

An abandoned Jewish sanatorium is tucked within the woods of Poland.