The final resting place of a legendary science fiction author and his fraternal twin sister who died as an infant.

A tiny nondenominational church harkens back to the days of the first homesteaders in the region.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

When ecosystems collide in the arid Southwest.

The highest bridge in America was built for an almost unnervingly small amount of money.

Home to the largest urban bat colony in North America, estimated at 1.5 million bats.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

See massive fossils that are over 200 million years old in northeastern Arizona.

Odd outsider art installations surround a Gold Rush-era ghost town.

New York City's smallest piece of private property.

Frank Lloyd Wright’s most iconic home dangles over a Pennsylvania waterfall.

This semi-secret garden in south Seattle emulates a traditional Japanese garden using the plants of the Pacific Northwest.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

In a 345-million-year-old cave that's 200 feet underground, dinner awaits.

The first declared National Monument in the United States.

Its buzzing collection honors vibrator history.

An immersive environment that is part haunted house, part choose-your-own-adventure, and part jungle gym.

One of the oldest continuously operating amusement parks in the U.S. is an open-air museum of Art Deco and neon lights.

The high point on the 16th president's eponymous roadway is marked by a massive version of his head.

This tea house was a hand-built gift from Boulder's sister city in Tajikstan.

This now-abandoned outcrop is an important Native American spiritual site, overtaken by European settlers and mining pollution.

This unassuming building houses one of the world's most extensive collections of cars created by automotive legend Carroll Shelby.

In the middle of a busy airport, a statue honoring the astronaut who told Houston that Apollo 13 had a problem.

In a dry, neglected cemetery lies the unassuming grave of a soldier vilified in life but celebrated in death.