This picturesque island graveyard is the final resting place of dozens of notorious pirates.

This monument is a stark reminder of the horrors of the Zanzibar slave trade.

This sacred, circular cave is lined with pools so clear and still that it's hard to tell where the water begins.

This mysterious, medieval cathedral remains unbuilt but fiercely protected.

Neither bomb blasts nor heartbeats escape the giant ears of this super sci-fi Arctic outpost.

The "Gateway to the Arctic" connects Barrow's indigenous population with the sea and its traditional industry: whaling.

This ghostly Alaska village still clings to a steep cliffside despite having been abandoned for over 50 years.

A war relic that has sat undisturbed since it crash-landed near Arno Atoll.

This volcano in the Philippines is believed to have miraculous healing powers.

A vast personal collection of World War II artifacts unearthed over many years by a father-son duo.

This collection of reclaimed landmines acts as both an exhibition of their deadly history and as a shelter for children affected by them.

A battle between nature and architecture in the Cambodian jungle.

Though it was originally dedicated to the Hindu god Shiva, Baphuon was converted to a Buddhist temple in the 15th century, complete with a massive hidden statue.

Take a hidden path to the mouth of the cave to watch millions of bats swarm at sunset.

A gruesome memorial for those lost in this area during the Khmer Rouge genocide.

A tangible and sobering reminder of an atrocity that took place during a secret war.

The world's most remote permanent settlement on an active volcano.

The tallest mud-brick structure in the world has been standing since the 1500s.

An ancient Roman snake god, carved expertly into stone.

These 7,000-year-old cave paintings depict life in Neolithic Spain.

This set of Berber granary caves is now an interpretation center for the cave window structures in the Clarino valley.

For many years, the origin of these enigmatic artificial caves was the subject of debate among historians.

A burial vault located under Tiber Island in the middle of the Italian capital.

This 11th-century Greek monastery has renowned mosaics and relics of a brutal past.