On this Puerto Rican island, many abandoned naval ammunition bunkers sit open while a few have been padlocked by locals as personal storage.

Decorative shell walls built in the 1940s sit atop an ancient midden created by the Calusa Native Americans.

Fortified homes of highland warriors that are still in use today.

According to Greek mythology, this natural spring is the home of a freshwater nymph.

Hundreds of tree trunks and Welwitschia flowers populate this living fossil haven.

Estimated to be more than 5,000 years old, this yew may be Britain’s oldest.

A former salt mine is now a cool picnic spot for families and asthmatics.

Legend has it these caves were created by a deity called Ogba, who is said to live inside the winding subterranean caverns.

Tubing through a cave lit with glowworms is a magical underground experience.

The Cape of Good Hope is not quite as low as you can go on the African continent, but it's still geographically significant.

An unexpected must-see for fans of Star Wars who find themselves on the beautiful island of Sint Maarten.

Where condemned pirates met their grisly end at the gallows on the River Thames.

The bizarre story of the mysterious death and hidden treasure of one of Sanibel Island's early homesteaders.

The notorious pirate William Kidd might have buried his treasure around this local pond.

Seven people are buried in the middle of what's now a movie theater parking lot.

A mixture of strange symbols, ciphers, words and cryptograms carved in 1876 remain unsolved to this day.

A mysterious concrete hand reaches out from between the stones of Uniwersytecki bridge.

Crystal hunters can dig for their own stones at this DIY mine in Arkansas’ quartz belt.

A Japanese pilot crash-landed on this Hawaiian island after the Pearl Harbor attack and terrorized locals for a week.

Law-protected wreckage serves as a peculiar memorial for an almost forgotten World War II tragedy.

An abandoned aircraft sits submerged in a lake in the Alaska wilderness.

One of the most accessible undersea plane wrecks in the world.

The wreckage still sits at the exact spot the plane crash-landed in 1945, carrying 1,000 pounds of explosives.

The secluded site of a 1943 plane crash and amazing rescue is only accessible by hiking through the woods.