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

A surreal museum of extraordinary industrial objects.

Breathtaking and huge 430 year old maps of Italy.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

The best preserved Paleochristian basilica in Rome hides a number of oddities and secrets.

This is the oldest Roman-made bridge in the city still existing in its original state.

An ancient Roman temple first dedicated to an emperor's wife is now a church.

This small, ancient Roman temple was once a church dedicated to the patron saint of penitents.

Also known as the Square Colosseum, this building is a prime example of fascist-era rationalist architecture.

This curious, round temple is the oldest still-standing marble building in Rome.

Gods clash with machines in a power plant regenerated as a museum.

A Nesting Doll of Churches.

Remarkably preserved body discovered in a peat bog.

The 20-mile causeway that separates the Netherlands from the sea.

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

A set of seven houses, each built in a style that represents a European country.

A dark patch of the ceiling at Grand Central Terminal which was not restored is still stained brown by tobacco.

This subterranean oyster house has been the pearl of Grand Central Station since 1913.

The largest geyser field in the southern hemisphere is a spectacular sight.

This daunting 1st century fortress was purportedly the site of one of the most dramatic revolts of the Jewish-Roman wars.

Palace where the nearly un-killable Rasputin was murdered.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

Pablo Neruda's custom-built lover's nest was made to remind him of the sea and named after his mistress' hair.

Quito's historic, main square dates back to the 16th century.