The glowing blue Nymphaeum of Emperor Tiberius.

Geothermal waterfalls in Tuscany.

Stalactites and stalagmites in a beautifully lit cave.

Pompeii's less famous neighbor is still revealing her secrets.

Renaissance villa and gardens complete with a tormented colossus.

The underground sanctuary of a mysterious ancient cult.

The middle finger of modernity.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

The only known mosaic depicting the Greek god of sleep, Hypnos.

This World War I fortress is the perfect place to catch a Montenegrin sunset.

A curious cave church carved into the face of a cliff.

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

The legendary cliffside castle of three-time Voivode of Wallachia, Vlad the Impaler.

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

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

The view that inspired the scenes of Dracula's first landing in England.

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

Ruins of an early Roman Christian church dating back to the 4th to 5th centuries.

An architectural marvel that spans the Arda River, and has stories of a haunted past.

Bizarrely shaped rock formations in northwest Bulgaria come with equally bizarre legends.

This massive concrete sculpture is said to be the heaviest communist monument on Earth.

Crossing a suspension bridge above a forest is the only way to reach this 12th-century monastery.

The site of many battles and tragedies, including the 40 maidens who leapt into the sea.