The world's longest known cave system.

A island reachable by a causeway at low tide is possibly one of the earliest Western European locations to be identified in text.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

A seemingly endless landscape of pure salt stretches far across Bolivia.

This Buddhist temple is home to the graves of the Japanese national legends, the 47 Ronin.

Strange rock formations tower above the river that snakes through this enchanting Icelandic canyon.

An abandoned saucer-shaped monument in the Bulgarian mountains.

Every equinox this Maya pyramid puts on a spooky ancient light show.

This tipsy office building in downtown Prague was originally called “Fred and Ginger.”

Swarovski's museum/theme park is a fake diamond fantasia overlooked by a giant.

A sculpture of a salmon swimming through a brick building.

One family's environment-friendly hobbit-house in Wales.

This Costa Rican topiary park is a surreal garden of unearthly delights.

This centuries-old Italian chapel hangs midway down a sheer cliffside.

Stonehenge has nothing on Castlerigg’s views.

This modern labyrinth lies in the shadow of a ruined medieval castle.

The ruins of a 19th century shelter run by the Independent Order of Odd Fellows.

The Master of Magnetism dominates the walls of a scrap metal yard to keep graffiti artists at bay.

The sound of swaying stalks in this stunning grove has been named a governmentally recognized sound.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

The beautiful baroque library of the Hapsburg empire.

The only swimming pool listed on the National Register of Historic Places is emptied and refilled each day with naturally filtered water.