A submerged archeological park still holds the wonders of a Roman Sodom.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

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

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

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

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

The Pope’s secret escape route.

This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

The final resting place of the poets Shelley and Keats.

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

2300-year-old Roman road connecting the empire.

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

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

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."

An enormous, inside-out glass globe built in 1935.

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

An abandoned cemetery lies in ruins as the surrounding forest swallows it whole.

The world's only museum devoted to the wonders of fluorescence.

An emerald-green grotto just a short trip from Austin.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.

A snapshot of the city's fascinating voodoo culture.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

The mysterious, fantastical woodland inspiration for "The Lord of the Rings."