A mysterious inscription may hold a clue about the "Lost Colony" of Roanoke.

These haunting ruins of a 700-year-old Prehispanic city have witnessed centuries of wars and massacres.

The courtyard of this small Marinid madrasa is a dazzling example of intricate Islamic architecture.

Transport yourself to the 1980s era of video games at this themed restaurant and bar.

Islanders once used this dramatic, otherworldly landscape to hide their cattle from Viking raiders.

This imposing 20th-century castle was abandoned before it was ever completed.

Nevada's largest cactus collection stands outside a candy mogul's small factory.

A sixth-century Byzantine cistern hidden below a modern carpet store.

One of the world's largest pyramids stands within El Mirador, the "lost city of the Maya."

The patron of this extravagant Art Nouveau confection insisted that nothing less than a boat should project from its facade.

This observatory within Europe's first dark sky park offers stunning views of the night sky.

Three sinkholes filled with warm, crystal-clear water reached by a horse-driven cart on an old train track through the jungle.

Anonymously sculpted and donated, these sculptures made from poetry books and pages are sprinkled around the city.

This neighborhood of futuristic ball houses looks like an alien settlement in a science fiction film.

A delightful but little-known public observatory and planetarium in Munich.

The ruins of a medieval village that was abandoned after a 19th-century inferno.

The oldest arboretum on the Dalmatian coast doubles as the gardens of Kings Landing in "Game of Thrones."

A fascinating assortment of cave dwellings, medieval ruins, and sarcophagi are being devoured by the forest.

A pyramidal marker where the borders of Venezuela, Brazil, and Guyana meet on top of Mount Roraima.

A leafy, peaceful oasis nestled in the heart of Glasgow's busy south side.

A small and surprising passageway in Saint Petersburg devoted to the Beatles.

Trek into the depths of the cave where 17,000-year-old paintings exist alongside 400-year-old graffiti.

A jungle in the heart of São Paulo reminds visitors of what Brazil looked like untouched by man.

The largest puppetry museum in the United States houses the world's most complete collection of Jim Henson artifacts.