Whitewashed mosque contains the world's largest carpet.

The opulent car collection of an eccentric Sheikh housed in his own private pyramid.

Feed it cash, get your very own gold bar.

Planned as the world’s first zero-carbon city, it had lofty ideals—but is only 5 percent completed and aiming for 50 percent carbon-neutral.

This tunnel entrance is built to resemble a grand castle but no one is quite sure why.

This ancient Irish tower could easily have stood in for Rapunzel's prison.

Wallabies live naturally on this Irish island.

Dublin's "Dead Zoo" serves as a window to Victorian museum design.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

A museum that cashes in on its infamous little people while teaching you a thing or two about the Irish fey.

Where commuters walk through remnants of an ancient Greek necropolis.

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

Europe's largest prehistoric mound – burial site of a legendary king?

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

Historic medieval fortified city in southwest France.

17th century streets hidden under Edinburgh were once a breeding ground for the black death.

The world’s largest LED display, built over an F1 race circuit.

The biggest and deepest Cold War bunker open to the public can be found in southeast England.

One of the few standing Roman lighthouses and a labyrinth of tunnels are a couple of the secrets at this historic castle.

Both church and state get put to the torch in this annual festival in the "Bonfire Capital of the World."

England's most notorious suicide spot.

This hilarious English intersection is an automotive whirlpool.

The largest stone circle in the world has ended up bringing up more questions than it has answered.

A minotaur, a labyrinth, and a dubious restoration pull in visitors from around the world.