Walk into an underground archeological dig, the site of the Roman Forum that was once the center of Valencia.

The odd cement nubs littering this Spanish square are actually the entrances to a series of buried silos.

A landscape decorated with enormous skull sculptures.

The bizarre home and sculpture garden of an eccentric artist.

The largest underground church in Europe.

Explore this medieval cathedral by trying to spot all the malevolent monsters hiding in its beautifully colored windows.

Extensive private collection of authentic Medieval devices used for human torture and execution.

Ivy-covered Medieval tunnels cut through this charming town in France's Loire Valley.

Houses are tucked between, on, and underneath giant boulders.

An abandoned mine now resembles a post-apocalyptic landscape of derelict buildings and blood-red pools of water.

A 12th century church completely covered in shells.