A stone slab in Madrid marks the point from which the distances of Spain's national roads are measured.

The doodles of a genius line the walls of a secret room under the Medici Chapel, where they were hidden for nearly 500 years.

Secret refuge and museum of the Duke of Florence.

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

The middle finger of modernity.

Those who own or stay at this 500-year-old, allegedly cursed house often meet terrible fates.

Hanging within this medieval church are the bones of a beast allegedly slain by a fourth-century saint.

As can be expected from a centuries old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

According to tradition this is the oldest church in Venice, but its actual age is a mystery.

This eclectic architectural gem played witness to Zurich’s colonial past.

This charming fountain honors Felix Salten, the creator of the iconic storybook deer.

Long tunnels run under the ancient chariot racing circuit to the tower.

A century-old prison in the heart of Vilnius is now a lively bar, dance club, and artist residency.

A site where “the ravages of the war are more striking…than any other place in contemporary Spain.”

Stunning Roman aqueduct used for 1900 years and still standing.

Spanning the El Chorro gorge, this pathway used to be one of the most dangerous crossings in the world.

A museum dedicated to the Spanish occult in a town that was terrorized by the Inquisition.

This camera store in Milan holds one of Europe’s largest collections of luxury-antique cameras.

The odd depiction of the Virgin Mary and baby Jesus is rooted in the Catholic Church's eradication of Catharism.

Just across from the "Last Supper" painting is the famous painter's vineyard, a gift received for creating the masterpiece.

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

Long-abandoned art nouveau baths beneath Milan's Piazza Oberdan.

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

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