An ancient passage filled with stalls selling used books, once frequented by Vincent Van Gogh.

A stunning 18th-century site where pilgrims ascend by a series of punishing stairs only to return via funicular.

More gold than anywhere else, ever.

One of the camera company's former manufacturing buildings is now a museum dedicated to its history.

The ruins of the suspension bridge hang over Kingsbury Run as a ghost of racial prejudice.

A wall of chewing gum moonlights as collective art.

The oldest automobile museum in the United States.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

The portrait of a man from Japan who sent weekly letters to a Dutch hotel he never visited.

The oldest residential street in Europe also features an optical illusion.

A perfect replica of the beloved show's first set.

Inside houses a vast collection of military aircraft and missiles spanning the ages.

Inside this wonderland of weird, visitors are treated to a collection ranging from skeletons to haunted artifacts.

A castle built by an eccentric medieval enthusiast in rural Ohio.

The largest earthwork effigy in the world.

How did a massive marine arthropod find its way to landlocked Ohio?

The world's third-largest crystal sphere has sat in the Penn Museum since 1927 with the exception of one outlandish theft.

A gothic palace of endless stalagmites and pseudoscorpions waits within one of the world's most beautiful caves.

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

John Tyler never got to be buried at his beloved home, but every pet his family owned since has been.

A wacky two-story folk-art assemblage of carved and found objects, with lights, motion, and sound now in need of financial support.

Built as a gift to the hottest tastemaker of the time, these hidden quarters remain an Art Deco showpiece.

The mounds at this site were reconstructed with the help of archaeologists and historians.

A unique collection of military history dating back to the American Revolution.