An otherworldly "cave" created by an artist in a Hong Kong factory building.

This hulking behemoth is actually five interconnected towers built in the 1960s.

Once a year, at exactly 11:11 a.m., this monument comes to life.

An overlooked monument to the celebrity gangster who helped put the sin in Sin City.

A giant open-air sculpture made of over 200 full-sized boats.

This incredible collection of vintage pinball machines can be played at 25 cents a pop.

This collection of neon icons is preserving Arizona's history, one sign at a time.

This collection of vintage signs reflects the long and colorful history of this Arizona town.

Originally conceived as part of a proposed Arizona State Capitol building in the 1950s, this structure built in 2004 stands as a monument to the architect's legacy.

An open-air, roadside eatery celebrating a historic indigenous cuisine of complicated significance.

Come for the pizza, stay for a performance on the world's largest theater pipe organ.

The exit of the largest prisoner-of-war escape attempt on American soil during World War II.

This iconic 1958 tower welcomes air travelers to Tucson with neon-lit letters and architectural style.

This scrap yard doubles as a naive art gallery full of found art and farm animals.

Bootleggers ran booze beneath this building before (and after) Route 66 appeared beside it.

A mysterious "wedding cake" castle in the middle of the urban desert.

In Tucson a giant metal snake helps pedestrians cross a busy highway.

Thousands of Mexican Free-Tailed Bats soar around an abandoned storm drain at sunset each summer.

This golf ball–shaped former desert real estate office now houses a UFO museum.

Limestone caves with spectacular showcase chambers.

On the outskirts of a reborn ghost town, a decaying post office remembers the bad old days.

Ancestral Puebloan ruins, natural arches, and box canyons abound in this seldom-visited corner of Monument Valley Navajo Tribal Park.

America's only nuclear missile silo open to the public.

A self-built castle made by a mysterious man.