It houses the remains of a 17th-century version of the Titanic.

A hidden bathhouse in one of Stockholm's oldest and busiest neighborhoods is open to anyone who can find it.

The mystic whose incorrupt corpse still attracts the faithful.

Rome's ancient Etruscan rival, now a park full of ruins.

A modern sliver of architecture in Roma.

The "Greatest Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

An abandoned Roman salami factory has found new life as an art space home to 200 squatters.

The martyr's wax-enhanced skeletal remains lie preserved in a glass case in the Santa Maria della Vittoria in Rome.

An Italian ghost town that fought obscurity, until a mysterious illness brought it to its knees.

This Roman arch marks the location of an ancient gate at one of the Seven Hills of Rome.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

This ancient Roman prison is decorated with an upside-down cross not as blasphemy but as saintly tribute.

A hospital where antique dolls are given new life.

This former Roman Catholic Church still contains the embalmed hearts and organs of 22 popes.

A fairy tale castle in modern Rome.

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

Jesus' footprints and the first catacombs in the world.

Architectural monsters are devouring this palace's every door and window.

The skull of the patron saint of lovers lies in the Basilica di Santa Maria in Cosmedin—maybe.

The final resting place of the poets Shelley and Keats.

2300-year-old Roman road connecting the empire.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

At the crypt of St. Mary of Eulogies and the Dead you are left alone to ponder mortality among piles of skulls.

The underground sanctuary of a mysterious ancient cult.