Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

The remains of Alfred Nobel's first nitroglycerine factory can still be found on the shores of a Swedish bay.

This Stockholm light tower can be controlled by anyone with a smartphone.

Stockholm's deepest subway station is also a stunning ecological wonder.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

Tucked away in a Prague park, a statue beloved by romantics honors a poet so nice they buried him twice.

A bus with a butt and biceps to put Olympic athletes to shame.

Microscopic scenes; some call it novelty, some call it art.

Abandoned railway line circling the city of Paris.

Remains of Roman amphitheater hidden in a sleepy quarter of Paris.

Egyptian Revival movie palace abandoned for decades and restored in 2013.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

Lyon, France is home to two remarkably preserved Roman theaters, one dating back to 15 BCE.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

A medieval military street hidden beneath a charming French fishing village.