South of Bologna, a limestone grotto with a protruding waterfall and a floor full of cave pearls.

This picturesque Umbrian city has a subterranean side that has long remained hidden.

This quaint Italian town keeps losing ground as the sides of its plateau slowly erode.

Gigantic mosaic sculptures of the figures on Tarot cards fill this colorful Tuscan garden.

This network of roads is one of the most unique Etruscan creations ever discovered.

This 16th-century monastery has been turned into a surrealist architecture compound.

A unique Tuscan hideaway acts as an art mecca as well as a hotel.

Visit a secretive crypt before it crumbles to dust.

Take a giant yellow bird cage to the top of Elba's highest mountain.

This Tuscan lake hides a 13th century town that is still visible when the water recedes.

Explore the quarry where the marble was sourced for Michaelangelo's David.

This beach-side arcade is believed to be the oldest penny arcade in America.

Now home to hardy plants, these sand and gravel dunes once held back a massive prehistoric lake.

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

A soon-to-be-forgotten roadside spectacle loaded with local lore.

"Dark Sky Park" is heaven on Earth for astronomers, one of the rare U.S. locations with no artificial light pollution.

Remnants of a storybook amusement park hidden behind a strip mall.

Dance on a hand-hewn log floor padded with bouncy boxcar springs at a saloon built in 1883.

The remote outlaw hideout of Jesse James, Butch Cassidy, and the Sundance Kid.

A classic carnival ride that was carved to be untouchable.

A sprawling museum located on the former site of the Orphan Girl Mine.

A working ranch doubles as a sustainable hub for world-renowned classical music and large-scale sculptures.

A collection of huge, site-specific sculptures sitting in the Montana woods.

A classic mystery spot complete with spots that are said to make you shrink or grow when you stand on them.