A musical instrument played by the sea.

Just a few miles from Novalja, a strange geological oddity has left scientists baffled.

This truly palatial work of Communist-era architecture now sits crumbling on a Croatian beach.

Now abandoned, the world's first torpedo factory is crumbling into the sea.

Croatia's "hairy stone" fortress is one of the most well preserved Istrian castles.

An ethereal glowing blue ocean cave in Croatia.

This overgrown mountain village has been abandoned for nearly a century.

These mysterious petroglyphs in Vermont reflect a troubled history in the treatment of Native American culture.

This whimsical park encourages its visitors and wildlife to roam on and around the various works of art.

A Kansas grassroots sculptor decorates the local roadways with his sculptures made from found objects.

This multisensory alley has the ability to remind bustling citygoers to stop and smell the roses.

This hidden stream beneath Indianapolis makes an appearance in the best-selling novel "Underground Airlines."

Nature and art meet in this curvy creation

A flamboyantly decorated bridge signals diversity and fellowship at the entry to Indianapolis' Broad Ripple Village.

This former office building has been transformed into an immersive music venue and art space.

This mysterious hill seems to pull objects uphill.

Less a museum than a bizarre fantasy world created by artists and engineers.

Man-made geyser that rises to the exact height of the Gateway Arch.

An abandoned meat mecca now serves as an excellent locale for urban exploration.

Giant works of art interspersed throughout meadows and woodlands offer a new discovery at every turn.

Curious cave that stays a cool 56 degrees all year long.

This majestic tree has survived 400 years of storms, droughts, and floods, and is a beloved natural landmark in Missouri.

An abandoned concrete jungle surrounded by a lush park.

Undone by Prohibition, this abandoned brewery-turned-flour mill is now ready for its third act.