The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

The largest stone moai on Rapa Nui.

This hunter-gatherer architecture is believed to be the oldest religious complex known.

The largest earthwork effigy in the world.

A real flying saucer, contracted by the U.S. Air Force.

The only remnant of a small mining town is an abandoned railroad tunnel that is steeped in ghostly lore.

This moving cemetery sphere is a slowly rolling stone.

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

The taxidermied remains of Charles Dickens' pet raven, which helped inspire one of Edgar Allan Poe's most famous poems.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

The fairy tale castle of the "fairy-tale king."

The birthplace of an eccentric alchemist and possible inspiration for the fictional reanimator of monsters.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

The former site of an all-but-forgotten colonial landmark is now remembered by an often overlooked bas relief.

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

This massive boulder is either a unique rock formation created by glacial melt or a magic energy vortex.

The boulder on which Alexander Hamilton laid his head as he died can still be visited on the New Jersey coast.

Final resting places of a husband and wife who became famous for their claims of extraterrestrial abduction.

The final resting place of the great escape artist, where some still gather to wait for his escape from death.

This unmarked and unloved Manhattan subway grate created one of the most iconic images in American cinema.

A pedestrian island in the middle of world-famous Times Square emits a strange (and purposeful) humming noise.

Hidden in an ordinary Midtown building is a one-room museum dedicated to the greatest escape artist.

A dilapidated dock tells the story of Titanic's missed arrival.

This Wall Street bar was once a hub of revolutionary activity where Washington famously bid farewell to his troops.