These ancient ruins were the final resting place of King Henry II's mistress.

At this cozy bar tucked down a hidden Galway backroad, Guinness makes the Gaelic come out.

Ruins battered by centuries of war and disaster offer a wondrous glimpse of medieval Ireland.

This Neolithic passage tomb forms part of a World Heritage Site.

The ancient tomb acts as a calendar that keeps perfect time.

A sacred well steeped in Pagan roots on the West Coast of Ireland.

This natural sea arch highlights Ireland's rugged coastal beauty.

This quarter-mile tunnel under the Bluff in Pittsburgh bends at a 45-degree angle.

There's a labyrinth of medieval chambers hidden deep below a 15th-century pub.

The English Civil War began right here in 1642.

An engineering error ensured this cavernous 350-foot-long subterranean thoroughfare was never used as intended.

A living maritime paradox still floats in the same lake where it was built and resurrected... or was it?

The site of America's first commercial oil well essentially disappeared after the town went bust.

Where the oil industry began.

One of the oldest living oak trees in the Southeast.

The uniquely-designed winter home and sculpture studio of Anna and Archer Huntington.

A haunting—but not haunted—chapel remains in the woods.

Take a stroll through this centuries-old tunnel of enormous moss-hung evergreens, nestled among the grounds of America’s first public sculpture garden.

This former hunting grounds that once attracted U.S. presidents and other luminaries. Now it’s a privately owned research reserve dedicated to environmental sciences.

Steinbeck's old stomping grounds, immortalized in Cannery Row.

Greenery covers the face of a gently-dripping waterfall deep in the mountains of central Sardinia.

A striped 12th-century basilica sits in the countryside of Sardinia.

This weird, elephant-shaped rock also hosts two ancient tombs.

Mysterious tombstones thought to be remnants of Atlantis.