The best preserved Paleochristian basilica in Rome hides a number of oddities and secrets.

A forgotten "city of water" underneath the famous Trevi district.

A Nesting Doll of Churches.

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

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

2300-year-old Roman road connecting the empire.

The underground sanctuary of a mysterious ancient cult.

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

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

The pile of books behind the dignified writer gave the statue a most undignified nickname.

An extensive collection of reliquaries containing the bones of saints housed in the largest Catholic church in Venice.

Go inside to really appreciate this 500-year-old technological masterpiece.

This community on a small Venetian island has taken to painting their houses in bright neon hues.

The holes in this wall provide a glimpse into Jewish life in Budapest, both past and present.

A statue in Budapest's Liberty Square honors the former U.S. president's efforts to end the Cold War.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

Museum dedicated to the terror regimes of Hungary.

Once the home of a hermetic monk, this cave now houses a small church.

The bust of Romania’s most notorious ruler, Vlad Dracula aka "Vlad the Impaler," keeps watch over the ruins of his medieval court.

This once-derelict building is now one of the most beautiful bookstores in the world.

This solitary monastery may hold the remains of Vlad the Impaler (but probably not).

The possible imprisonment of Vlad the Impaler here earned the medieval castle its nickname, "Dracula's Castle."

This fairy-tale castle would make Dracula (who is said to have been imprisoned there) jealous.

Underneath this Byzantinian church lies a necropolis filled with ancient tombs and the ruins of previous churches.