This romantic, decaying 13th-century ruin on the edge of Sherwood Forest is reputedly one of England's most haunted places.

Accessible only at low tide, the deserted island is dotted with World War II ruins.

This isolated structure beckons adventurers with sublime views of the Faroe Islands.

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

An abused and forgotten metropolis, abandoned for centuries.

The world's first experimental nutritionist is memorialized as the "Hippocrates of naval medicine."

Legend says these rocks used to be hunting dogs, a story that may have inspired Sherlock Holmes' most famous case.

A pub that is literally in the middle of nowhere, but continues to do business.

What happened to the three lighthouse keepers who vanished from this place remains a mystery over a century later.

A small island hides in plain sight on Austin's Lady Bird Lake.

Hidden above a drug store on a nondescript corner of Lincoln Heights is a private clubhouse for intrepid explorers.

A tiny, remote island packed with wonders both natural and geeky.

The highest peak in the United Kingdom has a history of physics, specters, and a pilgrimage of strange objects.

The most iconic structure in Scotland has been home to bishops, colonels, and Sean Connery characters.

The beautiful baroque library of the Hapsburg empire.

The oldest bibliophilia club in America, with exhibitions on historic books and graphic arts.

A 300-year-old tea shop that brought tea to the English people, not to mention the Queen herself.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

Hundreds of hidden passageways weave through the old quarters of Lyon.