A wall of chewing gum moonlights as collective art.

A world-class observatory in the California desert.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

An enormous, inside-out glass globe built in 1935.

Where there's quartz, there must be gold. Thus is the story of the mines of Julian, and the titillating times of the Gold Rush.

A model of a dinosaur that was named for Andrew Carnegie stands outside the museum that also bears his name.

The world's first time capsule lies behind a welded steel door in Atlanta.

The ruins of a cotton mill that was burned in the Civil War are still hidden in a Georgia forest.

The grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

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

The world's largest squirrel statue clutches a pecan bigger than your head.

This unique structure in suburban Austin is made up entirely of other people's castaways, and constantly changing.

Turning night into day in Victorian-era Austin to thwart a serial killer.

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

No one knows the meaning behind this giant sculpture of a nude woman with a fork riding a rooster in Havana.

Once a favorite playground for the world's most illustrious guests, Hotel Nacional's secret weapons and bunkers reveal a more menacing side to its golden history.

A focal point of the Cuban government, this city square features one of the most iconic images in the country.

An old slave lookout in Cuba's historic sugar cane fields.

This imposing memorial contains the remains of Che Guevara — and 29 other guerrillas who died with him in Bolivia.

A nuclear power plant abandoned along with an international allegience.

The only royal palace on U.S. soil has been a territorial capitol, a military headquarters, and a prison for a queen.

Maybe the only missile installed in a public park, this Cold War leftover was one of the first to carry a nuclear warhead.

An oil baron's wild paradise and the winner of an ill-fated air race.