An abandoned facility that has become a place of ritualistic satanic worship, or so rumor has it.

This sprawling 18th-century cemetery features unique and beautiful gravestones, including one shaped like a tree.

This whimsical castle of grottoes was the labor of love of a French postman, and one of the greatest achievements of outsider architecture.

More than 300,000 historical artifacts from the famous music venue, from Duke Ellington's handwritten score to The Beatles' booking slip.

The oldest family-run luncheonette in New York, last renovated in 1948, still serves food and drinks the old-fashioned way.

A kaleidoscopic warehouse-maze of handmade neon signs.

An Arizona museum with a collection of pharmaceutical oddities, including a jar of a gangster's chewed gum.

The oldest Buddhist monastery in Mongolia has survived centuries of invasions, political shifts, and religious purges.

Martin Bricelj Baraga's monolithic sculpture measures the blueness of the sky, and changes color to match it.

This large midwestern cavern features impressive rock formations and an underground waterfall.

The "Seinfeld" diner.

In addition to fine dairy products, the world's most beautiful milk shop also offers a feast for the eyes.

Most-visited and most-photographed slot canyon in the American Southwest.

The world’s first hotel to be run by robots.

A tongue-in-cheek arcade where the games are based on everyday life.

A psychedelic labyrinth on the San Francisco bay.

This former coal gasification plant found a curious second life as a popular public park.

Read between the lines of the subway map to find the hidden abandoned Civil War fort.

The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

The haunting, dilapidated remains of a former poorhouse on Staten Island's Greenbelt.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

A crumbling hospital from the 1850s on Roosevelt Island.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

A gigantic sculpture garden is packed with innovative oddities.