There are many of life's mysteries that will always be bigger than we are, from the Bermuda Triangle through to the noises that come out of Cardi B's mouth.
One of the things we'll always be truly curious about, however, is the puzzling case of Area 51, the top-secret military base in the Nevada desert. Recently, of course, it has become the subject of a Facebook event, in which more than one million people are planning to 'storm' it.
Very little is known about the mysterious site, largely because anytime someone gets close they're promptly stopped and forced to withdraw - with one man even shot dead back in January after he tried to enter.
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Because no one's allowed anywhere near the highly guarded site, many have had to focus on the surrounding area, which has become something of a hotspot for alien-themed diners and hotels.
Oh, and a mailbox, which is now one of Nevada's most unlikely tourist checkpoints.
Sitting on a dirt track in the middle of nowhere, on first inspection there's not much explanation behind the mailbox.
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But it turns out it belongs to Steve and Glenda Medlin and their cattle ranch.
According to the Los Angeles Times, the Medlins moved to the ranch in 1973 - a time when there was no talk of aliens or UFOs in the area and no home delivery for mail.
As the area became more built up, it grew into the town of Rachel, and postal workers began delivering mail to people's homes.
It was at this point the Medlins decided to plonk a black mailbox at a spot that was around six miles from their home, close to Highway 375.
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Then came our obsession with all things extra-terrestrial, and soon Rachel became known for apparent flying saucer sightings.
The Medlins' humble mailbox, curiously placed in the middle of a supposed alien hotbed, soon gained attention, and people began to leave messages for aliens inside.
"They were waiting for the aliens to abduct them, and they were anxious to meet them," Glenda told the LA Times.
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"We'd just shake our heads... It was so asinine."
The mailbox's cult following grew so much that some people even started shooting it, in turn leaving holes in the Medlins' mail.
Understandably pretty frustrated, Steve eventually had to replace the iconic black mailbox with a newer, white one that was made from bulletproof material.
However, the Medlins' didn't completely turn their backs on the alien fanatics flocking to Rachel, as Steve later attached a second mailbox underneath labelled 'Alien Drop Box'.
Featured Image Credit: Flickr/notevenathingTopics: Area 51, News, US News