This grisly effigy displays an early Christian martyr who was skinned alive and beheaded.

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

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

A medieval stronghold rising over the ruins of ancient Roman villas along Rome's southern coast.

Ever hear of the Milazzo Cage?

A 15th-century monumental Latin inscription on this house celebrates Lorenzo Manilio's love for Rome.

The Italian revolutionary's legendary wife is portrayed on horseback waving a gun and holding her child in this memorial on the Janiculum.

The former home of an Italian artist is now a shrine to his ambitious works.

Remnants of a 4th-century church with vivid medieval frescoes and ancient sarcophagi hide beneath this old basilica.

St. Francesca Romana, patron saint of drivers, resides in the church she founded.

One of seven Jewish catacombs in Rome and one of only two open to the public.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

Nikola Tesla's ashes are held in a golden sphere, surrounded by his works.

This statue of a goat in boots is meant to represent the European Union.

A misnamed well, with a deep dark past.

A church of bones, decorated with 40,000 human skeletons.

A 19th century artistocrat's mansion, turned into a library, hidden in a modern library.

Some of the greatest minds in the history of Hungarian art and science converged in this café.

The amazing wonder cabinets of a very rich Austrian archbishop.

This set of concrete chambers resonates according to different notes of octaves.

This little gem in the Gulf of Riga has a very rich heritage and distinct culture.

An underground nightclub helped spark a "Singing Revolution."

Rusted cars, trucks, and buses form a fascinating collection of Soviet-era machinery.

The oldest church in the Estonian capital is home to over 100 fantastical cemetery coats-of-arms.