People have been living in the cave houses on this Italian hillside since the Neolithic era.

Venice's island of the dead.

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

An abandoned quarry hides an open-air gallery of huge sculptures, some made from the rubble of 9/11.

Skulls and skeletons are omnipresent in this church dedicated to souls trapped in purgatory.

Built on a medieval synagogue, this church has a burial crypt, tunnel system, and Jewish ritual bath hiding deep underneath.

The world's most active stratovolcano is almost always erupting.

Thousands of well-dressed mummies below a monastery.

This triumphal 16th-century arched gateway leads to the oldest street in Palermo.

A medieval wash house where people washed clothes in a river allegedly formed by the tears of a mourning nymph.

A 16th-century horror show built in a lovely Italian garden.

This astronomical clock is the second oldest in England.

A dark Victorian well house now plays host to mystical waters and pagan shrines.

This statue celebrating everyday life in Dublin has a few unsavory nicknames.

This colorful and fiery mural depicts the Irish folk story of the beloved hero Cuchulain.

The fairy tale castle of the “fairy-tale king,” this was also the inspiration for Disney’s “Sleeping Beauty.”

Spanish architects used seized Muslim gravestones to rebuild parts of the fortress.

An historic and oft-filmed spot for musclebound iron pumpers on the Pacific coast.

Legendary frontman of the Doors looms in this giant mural by famed Venice muralist, Rip Cronk.

Hollywood's most famous landmark, the "temporary" sign that has stood for decades longer than intended.

This picturesque horseshoe weir was first built in the 1600s to prevent flooding in the town of Bath.

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

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

The sign marks one of the endpoints to mainland Britain's longest overland travel route.