A little-known ruin with a convoluted history and a fascinating latrine drainage system.

A 12th-century church with a medieval fresco and an intriguing “Greek runestone.”

An otherworldly, fossil-rich cobble beach holds Viking graves, cairns, and other remains.

The tombstone of an unfortunate explorer who disappeared in the Paris Catacombs.

This natural marble cave is one of only five national monuments in Oregon.

The eerie remnants of an ancient forest were hidden under the sand for centuries.

This medieval sanctuary's tree-framed door looks like a portal to a mythical realm.

Despite its grandiose name, this enigmatic first-century void under the town is no cave, and it's possibly not a palace either.

Believed to be haunted, this old cemetery is beautifully adorned with Spanish moss hanging from the trees.

An extraordinary mix of Phoenician, Roman, early Christian, and Byzantine ruins beautifully set overlooking the Mediterranean.

This huge abandoned fortress hidden inside a mountain holds a world of subterranean secrets.

The ruins of a monastery where Saint Bridget of Sweden had her revelations recorded.

The little-known second castle that William the Conqueror built in York.

This beautiful and unmissable little museum is full of fascinating artifacts from Mesoamerica's great civilizations.

Developers built a Walmart around one family's plot and constructed a mausoleum in the parking lot.

The English bed-and-breakfast believed to have inspired Emily Brontë's novel "Wuthering Heights."

The medieval castle built as headquarters for the Pope's secretive Knights Templar.

The sole remaining outpost of a once-thriving South Carolina chain still sells “pic-a-nic” baskets.

An effigy of a trapped paratrooper dangles from a Normandy church to commemorate one remarkable D-Day event.

Once America’s most beautiful army base, this abandoned military fort on the coast of Monterey Bay has been left to the elements.

Even in death, he's still your huckleberry.

The verdant mossy ruins of a Franciscan monastery lie in the remote Sintra hills awaiting exploration.

The original resting place of Queen Cleopatra and Mark Antony's only daughter.

Thousand-year-old Viking runes adorn an ancient Greek lion at the entrance to the Venetian Arsenal.