An incredibly well-preserved piece of ninth-century Viking poop.

The little-known second castle that William the Conqueror built in York.

The graveyard with the highest IQ in Britain.

Local legend says Isaac Newton built this footbridge without any screws, bolts, or nails.

A open air theatre built on a cliff by an eccentric British woman.

A island reachable by a causeway at low tide is possibly one of the earliest Western European locations to be identified in text.

Perhaps the only prehistoric monument with its very own public bus stop.

A spooky juxtaposition of caves and graves gives this legend-filled cemetery a particularly haunting vibe.

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

An ancient Roman temple first dedicated to an emperor's wife is now a church.

This hidden Art Nouveau courtyard is an opulent feast for the eyes.

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

Architectureal fantasy quarter of Rome.

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

This old medieval prison tower has been a site of astronomical research for more than 250 years.

One of the world's oldest working clocks is curiously missing the Zodiac sign of Libra.

Something's missing between the arcades of the Palazzo della Ragione in "the city of the three withouts."

A whale rib was used to advertise the store by the arch that offered exotic goods from far away.

Pilgrimage site for star-crossed lovers.

It’s said this crypt was the setting for the tragic finale of the Shakespeare play.

Psychoanalyst Carl Jung reported a paranormal experience after visiting this mosaic-lined Roman baptistry.

Filled with goldfish swimming in a shallow pool of sea water, this ancient crypt is more wishing well than burial site.

High in the clouds of San Marino sits an ancient tower with some curious prisoner graffiti.

Some call this eerie forest of crooked trees the "Bermuda Triangle of Romania."