The largest stretch of the Berlin Wall is right on top of the former SS headquarters

This futuristic German spa allows visitors to float in a pool of salt water while zoning out to underwater techno.

The skeletal frame of a decommissioned gas-pumping station offers breathtaking views of greater Berlin.

The bunker where Hitler took his own life is hidden under this deliberately ordinary parking lot.

A prime example of socialist modernist architecture, wrapped in a enormous fresco about the media.

This water-tower-turned-high-end-apartment building was once the site of an early Nazi concentration camp.

Once a path for Jewish funeral processions, this unassuming alleyway is rich in local lore.

Inside this Jewish cemetery is a memorial to soldiers who deserted the German army and were executed.

Berlin's old airport.

Dedicated to the European Sinti and Roma peoples murdered during the Holocaust.

One of Amsterdam’s most popular cultural and recreational complexes is on the site of a former gas works.

The world’s largest street art museum.

A museum dedicated to the history of the diamond trade in the Netherlands.

A unique zoological park home to over 30 species of wild cats, both big and small.

The world's first funicular powered by a steam engine.

Lyon's miniature version of the Eiffel Tower was built as a statement in support of French secularism.

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

This fairy tale forest hides scenes from some of the more obscure and bizarre Western nursery stories.

A Netherlands hotel where you can sleep inside a wine barrel.

This Dutch statue is a monument to the fictional shrew who brought doom to the city of Stavoren.

The celebrated eyesore created by starry-eyed sweethearts.

Historic medieval fortified city in southwest France.

Yup, that's a 330-foot yacht passing over the highway.

The video game-themed street art first popped up in the French city.