Abandoned railway line circling the city of Paris.

It might not be as impossible to reach as its name would imply, but just about.

The world's most remote permanent settlement on an active volcano.

Napoleon’s home in exile, decorated with poisonous wallpaper.

This abandoned lighthouse looks like a rusting oil rig, but has managed to survive a number of storms.

This massive and eclectic collection is filled with thousands of sculptures, masks, and assemblages.

Live-in sculpture begun by one family in 1979.

France's highest manned weather station is the only one still inhabited by meteorologists.

This music school doubles as a store for unique, hand-crafted, and hard-to-find instruments.

This French "sea of rocks" is packed with stunning rock formations and its own medieval castle.

Cloistered comestibles are served with style at this French Orthodox monastery.

This army of concretions is an unexplained geological phenomenon unlike anything else in the world.

Located more than 600 feet beneath the North Atlantic seabed, this tunnel boasts the world's first undersea roundabout.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

One of the only places where Earth’s mantle lies above water.

A monument to the migrants who cross the dangerous waters between North Africa and a tiny Italian island.

Blue-green pools and smooth stones comprise one of Spain’s most idyllic hidden wonders.

Edison's cast-in-place concrete houses were a failure, but way ahead of their time.

This giant boulder is sandwiched between apartment complexes in upper Manhattan.

A boardwalk winds through this sliver of coastal nature hidden within Sydney.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

The fanciest public restroom in New York City boasts fresh flowers, art, and a classical music soundtrack.

A masterpiece of LGBT art has been restored in what may now be the most valuable restroom in America.

Norway has built what may be the world's most beautiful public toilet.