The Pope’s secret escape route.

Stone memorial that's said to predict the death of the pope and the site of the Cadaver Synod.

A fairy tale castle in modern Rome.

Architectureal fantasy quarter of Rome.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

Installed in an act of one-upsmanship, the annual sundial in this church is also a symbolic victory for the Gregorian calendar.

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

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

A sculpture serving as an homage to Pope John Paul II.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

An alchemist's "magic door" stands in the middle of a Roman park.

A Nesting Doll of Churches.

The yawning maw of this pagan visage is said to bite off the hands of liars.

The underground sanctuary of a mysterious ancient cult.

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

This ghost town in Belgium will lose its street art when it ceases to exist.

Australian Lake set aglow by Noctiluca Scintillans.

Millions of glowing microscopic organisms light up the waters of this luminous lagoon.

A mysterious light floating in the trees of Arkansas may be a piezoelectric effect.

A seemingly endless landscape of pure salt stretches far across Bolivia.

The world's brightest bioluminescent bay.

Bioluminescent firefly squid light up this Japanese fishing port.

Enormous underground chamber built to detect 'ghost particles' of the universe.