Gods clash with machines in a power plant regenerated as a museum.

2300-year-old Roman road connecting the empire.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

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

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

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

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

A wunderkammer of curious objects and intriguing art nestled within a hub of ancient Roman sites.

The spot where the fascist dictator made some of his most famous speeches including declaring war on Britain and France.

Jesus' footprints and the first catacombs in the world.

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

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

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

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

A 250-year-old timepiece-automaton adorned with golden mechanical birds, which still sing to this day.

This truly palatial work of Communist-era architecture now sits crumbling on a Croatian beach.

A gorgeous medieval library where the books are kept in chains.

A domed disco abandoned since the '70s now attracts artists and explorers under its unique roof.

This 6th-century church has the largest and best-preserved collection of Byzantine mosaics outside Constantinople.

Italian poet Dante Alighieri is entombed in this small mausoleum in Ravenna, and his hometown of Florence has never been too happy about it.

Filled with goldfish swimming in a shallow pool of sea water, this ancient crypt is more wishing well than burial site.

Contains some of the world's more disturbing wax anatomical models.

A dismembered holy head stares out from her beautiful reliquary at the St. Dominic Basilica.

A copy of the famous statue can be found in this Florence piazza, along with one of the most breathtaking views of the city below.