The mystery of this small, brick pond eluded its possibly only investigator until his death.

These 7,000-year-old cave paintings depict life in Neolithic Spain.

This freewheeling amusement ride is the last of its kind.

Harry Houdini plunged into the Charles River and performed one of his escape acts here in 1908.

Accessible only by boat, this centuries-old island fort never saw troops or combat.

An exact replica of a colossal Olmec head sits atop a pyramid within a Madrid traffic circle.

A tiny slice shop hides down an unmarked hallway in a Las Vegas casino.

The property contains 37 preserved animal effigy mounds constructed by Native Americans between 800-1100.

What began as a prominent Burning Man art piece is now an iconic symbol of downtown Reno.

An unpaid bill, a stolen stone, and a famous fashion designer rest peacefully alongside a heroine of Highlands history.

New Hampshire's first neighborhood is now preserved as a historic village with live action role players.

A spring purported to have healing properties lies just outside Scotland's capital.

The only thing these street signs will help you navigate is your imagination.

An unconventional and naturalistic sculpture depicting the artist marking his territory on an exterior faculty wall.

Dedicated to the neverending mathematical constant, this plaque next to a park bench was sponsored by an anonymous benefactor.

At the center of London’s oldest roundabout stands an obelisk that was erected in 1771, but spent several decades elsewhere.

A gift to the children of Boston, this bronze bear represents playfulness, a spirit of love, and the warmth of big hugs.

This 19th century Sioux City candy company is the home of the Twin Bing, a historic, chocolate-covered treat.

The Guinness Record holder as the "tallest cinema in the world" is a building with screens in almost every one of its 12 floors

An archway adorned with vulnerable flora and fauna.

A museum dedicated to telling lies in service of the truth.

This statue is a commemoration of the only place where Freud spoke in the United States.

The last standing piece of a famous Honolulu landmark.

One of the oldest, tallest, and most haunted lighthouses in America.