Its dark depths conceal millions of rare, delicate crystal formations.

An unusual library of dead things at the Rhode Island School of Design.

An enchanting work of outsider art, full of whimsical sculptures and carvings.

Surrounded by ash fields in Iceland, an impossibly verdant valley looks like something out of a fairytale.

This army of concretions is an unexplained geological phenomenon unlike anything else in the world.

This 1920s Dutch barge is now a floating bookstore.

The residents of the Neighborhood of Make-Believe live without much fanfare within the Pittsburgh Children's Museum.

This unusual rock formation looks like an apple that has been neatly sliced in half.

This small museum is an eccentric shrine to boyhood in the 1960s.

This 40-room dwelling tucked within a cliff was built by the basin's prehistoric residents.

A dollhouse full of taxidermy rodents, each one handcrafted and given a sordid past.

This small oasis of flora and art was created in remembrance of a local auto business owner.

This Boeing KC-97 tanker is now a restaurant for aviation lovers.

About as hidden as can be, this specialty coffee shop is wedged between multi-story buildings at the end of a dark, skinny alleyway in Seoul.

An abandoned car and strange wooden debris are among the scattered remains of the old sand and gravel quarry.

Visit the home of Sweden's beloved fictional character, Pippi Longstocking.

One of the last umbrella repair shops in Paris upholds the nostalgic art of umbrella making.

This abandoned Brutalist treehouse is a hidden architectural relic.

Check out a shovel along with your Shakespeare.

A unique piece of graffiti offers a little slice of local history and mystery.

More than 21,000 images fill this overlooked gem of a prehistoric site.

The land is full of geologic eye candy, such as otherworldly spires, mushroom-shaped hoodoos, and prehistoric fossils.

A Harvard-area eatery preserves the uncovered tiles of its century-old predecessor.

One of the American Southwest's most extensive collections of Navajo rock art.