A large grotto built in the 16th century amidst Florence's famous Boboli gardens.

The secret medieval communication system will whisk your words above the noise of the crowd.

An exclusive waiting room built for the royal family in the 1920s is hidden in Milan’s central station.

Da Vinci's equestrian statue, 500 years in the making.

Milan's duomo is covered in beautiful carving including a curious "dinosaur-like" beast.

A medieval church with largest and oldest collection of Renaissance frescoes in France.

There is a strange little carving of a person seemingly crushed by a pillar behind the remains of St. Thomas Aquinas.

The titular "little arch" near this Italian resort is one of the most popular diving spots in the country.

This elaborate hole in the ground was built as a sacred site for an ancient civilization.

This one-of-a-kind archeological site is home to strange prehistoric ruins, the original use of which is still a mystery.

Stalactites and stalagmites in a beautifully lit cave.

Two stone columns flank the grand Venice square, but there were supposed to be three.

Go inside to really appreciate this 500-year-old technological masterpiece.

This modern museum of Mediterranean culture is surrounded by a surreal concrete honeycomb.

This Parisian café sticks almost exclusively to an ethos of reuse.

Historic medieval fortified city in southwest France.

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

This stunning concert hall has become a symbol of Iceland's national recovery.

One of the tallest buildings in Iceland, and perhaps, the most visually impressive.

Medicinal spa created with the discharge from a geothermal energy plant.

Founded as a refugee camp, now a popular tourist spot.

Crumbling necropolis set high above Fez.

The oldest known university in the world is in Fez, Morocco.

Traditional 11th-century outdoor tannery.