The remains of Crystal Palace Great Exhibition of 1851.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

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

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

Dug as a secret royal escape route, the tunnel became a wartime bomb shelter and dumping ground for vintage cars.

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

An underground paleo-Christian burial site composed of the remains of several cemeteries and Basilicas.

The burial place of an obscure North African saint was turned into a macabre body preservation factory for the 17th-century Neapolitan elite.

Erotic art covers the walls of the largest ancient pleasure palace.

The walls and streets of the ancient city are peppered with penises.

This amazingly well-preserved villa just outside Pompeii boasts rare examples of ancient Roman paintings.

Legend says the people of Wiltshire got their "Moonraker" nickname from this small pond.

A winding cave grotto walkway built to provide employment for veterans after World War I.

The world's first underground farm is in a World War II bomb shelter beneath the streets of London.

An impromptu shrine appeared shortly after beloved "Torchwood" character Ianto Jones was killed off the show.

The only medieval bridge in Britain with its defensive tower still in tact.

Detailed sandstone carvings show an array of symbolism and adorable animals.

A quaint hamlet of nine cottages around a small green near Blaise castle.

Legend says this demonic carving inside a medieval cathedral was one of Satan's minions.

Discovered on a shipwreck after more than 400 years, this Renaissance ratter tells a very waggly tale.

Angels, demons, and tortured souls on a giant wall mural in a little church.

The only university zoological museum in London houses extinct animals, bizarre natural history specimens, and a Micrarium of microscopic creatures.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

Beasts and branches swirl in sandstone carvings, interrupted by one strange creature.