The Roman Emperor's lost summer home and grotto full of enormous sculptures sit along the Italian seashore.

Buildings from the fictional planet of Tatooine still litter the Tunisian desert.

Made famous by 'Star Wars,' these troglodyte homes face an uncertain future.

Most prolific publishing house in the 1600s open to the public.

Incredible labyrinth of man made caves.

Housing the groundbreaking maps and globes of Gerard Mercator.

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

Head underground and take a tour of the city's working sewer system, and see the underground river Senne, which defined Brussels for centuries before being covered in the 19th century.

Live out your childhood construction fantasies in this one-of-a-kind gyrating hotel.

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

This simple apartment may have inspired some of the most important theories in the history of science.

A nearly 500-year-old sculpture depicts a man eating a sack of babies, and no one is sure why.

The Swiss artist's bulbous and overgrown shape-shifting sculpture controversially graces the center of Bern.

This massive blockhead sculpture hides an entire library.

The design of this beautifully crafted building was inspired by Norwegian glaciers.

This floating sculpture of ice is a poignant reminder of nature's power.

This mysterious chalk figure of a horse has been recreated and restored for more than a century.

These stark white cliffs were spat up by the sea and are slowly being retaken by it.

The last bastion of Roman presence north of the Alps looms over a German town.

The birthplace of Karl Marx is now a museum dedicated to the communist revolutionary's life and work.

This giant geoglyph of mysterious origins is now the site of neo-pagan rituals.

England's most notorious suicide spot.

One of England's most famous churches hides a pair of little known architectural treasures.

Old ships and machinery fill a historic harbor in the city that's home to Europe's largest port.