Eco-village hidden in the foothills of the Alps that created a massive system of psychedelic underground temples.

This picturesque Umbrian city has a subterranean side that has long remained hidden.

One of several skulls claiming to belong to the beheaded St. John the Baptist is on display at this Roman church.

A sunken idol welcomes parishioners to Davy Jones' Locker.

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

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

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

This domed temple was built in a hidden cave mouth as a refuge for sinners seeking absolution.

These "anatomical machines" are only one of the many strange items in this Italian crypt.

Skulls from the plague of 1656 and World War II bombings are united by a cult dedicated to caring for the ancient dead.

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.

As can be expected from a centuries old church built in a canal city, the undercroft of this house of worship is beautifully flooded.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

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

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

Stalactites and stalagmites in a beautifully lit cave.

Renaissance villa and gardens complete with a tormented colossus.

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

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

Thousands of well-dressed mummies below a monastery.

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

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

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