This Roman arch marks the location of an ancient gate at one of the Seven Hills of Rome.

This ancient village and its adjoining cemetery have a beautiful history of death and remembrance.

Built by prisoners of war, the largest small-scale model ever built includes eight miles of tiny streams that now sit abandoned.

Scattered around Atlanta are little doors with big charm.

This centuries-old Italian chapel hangs midway down a sheer cliffside.

An ancient artistic garden parlor full of hidden water wonders.

This Italian foot path winds through the mountains via 52 individual tunnels.

According to the local folklore, the myriad colors of this lake are the result of a lovelorn wizard's blunder.

A sunken idol welcomes parishioners to Davy Jones' Locker.

Pilgrimage site for star-crossed lovers.

Medieval town turned hippie commune, once home to the secret foreskin of Jesus Christ.

The once forbidden "secret cabinet" of erotic art from excavations of Pompeii and Herculaneum.

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

Geothermal waterfalls in Tuscany.

Abandoned medieval hill town.

The glowing blue Nymphaeum of Emperor Tiberius.

Hidden in an Italian forest is a completely homemade amusement park that has taken a lifetime to create.

Stalactites and stalagmites in a beautifully lit cave.

Renaissance villa and gardens complete with a tormented colossus.

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

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

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

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

Hidden in a metro shop under a shopping mall, this small museum tells the story of one of the world's largest urban transit systems.