A huge musical instrument played by the ocean.

James Turrell's total color immersion art installation, hidden on the top floor of a luxury handbag shop.

This faux-seedy Japanese arcade is made up to look like a maze of alleys straight out of a cyberpunk dystopia.

These old stone ruins in the Oregon wilderness were once bathrooms and are steeped in legends of murder.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.

A 140-year-old castle with underground caves hidden in San Francisco.

A theme park that suffered massive flooding during Katrina was abandoned, and now proves irresistible to trespassing explorers.

The world's only museum devoted to the wonders of fluorescence.

An exquisite tunnel of cascading flowers.

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

A crumbling hospital from the 1850s on Roosevelt Island.

This dramatic landscape hidden on the Isle of Skye looks as though you've stepped into the magical realm.

A terrific purveyor of natural history objects and curios.

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."

Wondrous sandstone hoodoos where Native Americans collected clay for pottery, 9,000 years ago.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.

The installation’s official name, “You Who Are Getting Obliterated in the Dancing Swarm of Fireflies,” says it all.

An artsy hidden staircase leads to breathtaking views of San Francisco.

An Italian crevasse filled with abandoned buildings gives visitors a look at the world without humans.

A layered tribute to the work of mosaicist Isaiah Zagar.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

A magical place that lets you play in and explore the world of Studio Ghibli.

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

During prohibition, corrupt city officials ran drinking dens under the streets of Downtown Los Angeles.