In Tucson a giant metal snake helps pedestrians cross a busy highway.

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

One of Catholicism's four major basilicas has a series of papal portraits that are said to predict the end of the world.

The mystic whose incorrupt corpse still attracts the faithful.

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

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

This ancient Roman prison is decorated with an upside-down cross not as blasphemy but as saintly tribute.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

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

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

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

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

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

An ancient passage filled with stalls selling used books, once frequented by Vincent Van Gogh.

The attic of a four-century-old canal house hides a clandestine church.

Used as an example in one of the first dictionary entries for "museum" in 1706.

The beloved fantasy novelist is buried near a church containing a whimsical etched glass window full of Narnia favorites.

J.R.R Tolkien, C.S. Lewis, and other "Inklings" met at the Oxford pub to discuss the now legendary fantasy stories they were writing.

The Cambridge pub where Francis Crick announced that he and James Watson had discovered the DNA double-helix.

Numberless clock creates a meal of time for the dreaded, insectile Chronophage.

A measuring mishap led to these artificial stone ladies losing their stomachs.

Tucked away in the Tower of London is the weapon once used to execute high-profile prisoners.

The "lost friend” is the most famous of the six moai statues that were removed from Easter Island.