A once popular resort—said to be the vacation spot of gangster Al Capone—now remains abandoned in the woods of Arizona.

The biggest solar telescope in the world helps reveal the secrets of our sun.

Take a monster truck tour around an ostrich farm in the middle of the desert.

A nature and cultural preserve named for its multitude of petroglyphs carved by the Northern Sinagua people.

The highest point in Arizona is an oddly snow-topped peak within the otherwise arid state.

This 40-room dwelling tucked within a cliff was built by the basin's prehistoric residents.

One of the world's largest telescopes, stares into the night sky with two huge mirrors.

An artificial crater field that trained astronauts for lunar exploration.

This Arizona observatory is famous for investigations into Martian life, and as the place humans first spotted Pluto.

Witnessing the might of this dessert-colored desert waterfall is a rare, powerful treat.

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

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

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

The installation’s official name, “You Who Are Getting Obliterated in the Dancing Swarm of Fireflies,” says it all.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

Dramatic river bend surrounds a natural red-rocked pedestal.

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

Rippling sand dunes frozen in the Arizona rock.

One of the most well-preserved castles in Italy also contains a rare medieval example of a port fortification.

These wooden pipes were crucial to providing water to Medieval Edinburgh.

These massive concrete balls were used to mine gold in Virginia.

This National Natural Landmark is one of the best examples of a “mass wasting” in the world.

The residents of the Neighborhood of Make-Believe live without much fanfare within the Pittsburgh Children's Museum.

The now-abandoned tunnels were built for the transcontinental railroad on the route where the first wagon train entered California.