An enigmatic modern marker left next to a historic Roman site.

A secret hatch containing two parchments was discovered in this statue over 40 years after its installation.

The only remaining arch of the oldest stone bridge in Rome stands in the middle of the Tiber.

This ancient trail climbs the mountain where a Latin League cult worshipped Jupiter, its main deity.

A burial vault located under Tiber Island in the middle of the Italian capital.

This hydrochronometer was invented by a Dominican monk and is a prime feature in this garden.

This curious, round temple is the oldest still-standing marble building in Rome.

A magnificent waterfall is also home to the remains of a Roman hydraulic engineering system.

One of the most important yet well-hidden museums dedicated to the history of medicine.

One of several skulls claiming to belong to the beheaded St. John the Baptist is on display at this Roman church.

A collection of objects supposedly singed by the hands of souls in purgatory.

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

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

Mozart's skull may be held in this collection, but definitive proof continues to elude scientists.

These 12th-century catacombs carved into a mountainside were a place of mysticism and Christian hermitages.

Trick water gardens from 1619 featuring a 200 piece mechanical theater powered by water.

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

The precise origins of this pink sandstone temple are unknown.

This structure atop a craggy cliff in one of the most beautiful parks in Paris boasts an unbeatable view.

The tradition of open-air secondhand and antiquarian bookselling in Paris dates back to the Renaissance.

In the best of all possible worlds, everyone will get a chance to see this statue in which Voltaire's heart is interred.

Twelve grave-faced marble angels guard the emperor's tomb at Les Invalides.

Paris' fabled purveyor of exotic taxidermy and natural history curios.

A museum of magic with a Sadist past.