by It started as a bit of a joke, but now the US Air Force has told people not to go near Area 51.
More than a million people have RSVP'd to an event on Facebook, threatening to storm the top-secret base in Nevada, which some believe is home to aliens.
Thousands have commented on the page, which reads: "We can move faster than their bullets. Let's see them aliens."
A spokeswoman for the Air Force has told The Washington Post it is "ready to protect America and its assets".
Facebook user Jackson Barnes wrote on the event page: "Hello US government, this is a joke, and I do not actually intend to go ahead with this plan".
"I just thought it would be funny and get me some thumbsy uppies on the Internet. I'm not responsible if people decide to actually storm area 51."
But the Air Force isn't seeing the funny side.
"[Area 51] is an open training range for the US Air Force, and we would discourage anyone from trying to come into the area where we train American armed forces," the spokeswoman said.
What are the theories about Area 51?
Some conspiracy theorists think the US government has information on alien life and UFOs that they are withholding from the general population.
They think the Area 51 base - which was formally recognised in 2013 - holds captured aliens, their technology and crashed UFOs (unidentified flying objects) - something denied by the government.
Theories about the base started in 1989 when a man named Bob Lazar claimed in an interview on US TV that he was a physicist who had worked in Area 51.
He recently appeared on comedian Joe Rogan's podcast. There's also a Netflix documentary about him, which could have prompted renewed interest in his story.
Lazar said he had worked on taking apart a UFO and had read government documents describing alien involvement in life on earth.
He has no hard evidence or proof for what he's claiming, and no records of his alleged university physics degrees exist - but he definitely helped fuel the stories about Area 51.
As Thomas Bullard, author of The Myth and Mystery of UFOs says: "After trust between government and public eroded with Vietnam and Watergate, Roswell and Area 51 entered the popular vocabulary as bywords for official double-dealing."
Roswell is an area in New Mexico where an airborne object crashed in 1947.
The military says it was a weather balloon, but a theory has been widely held that it was actually a UFO that had crash-landed and then been covered up.
Despite the US government revealing in the 1990s that it was actually a nuclear test surveillance balloon, the incident still attracts lots of attention and conspiracy theories.
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More than a million people have RSVP'd to an event on Facebook, threatening to storm the top-secret base in Nevada, which some believe is home to aliens.
Thousands have commented on the page, which reads: "We can move faster than their bullets. Let's see them aliens."
A spokeswoman for the Air Force has told The Washington Post it is "ready to protect America and its assets".
Facebook user Jackson Barnes wrote on the event page: "Hello US government, this is a joke, and I do not actually intend to go ahead with this plan".
"I just thought it would be funny and get me some thumbsy uppies on the Internet. I'm not responsible if people decide to actually storm area 51."
But the Air Force isn't seeing the funny side.
"[Area 51] is an open training range for the US Air Force, and we would discourage anyone from trying to come into the area where we train American armed forces," the spokeswoman said.
What are the theories about Area 51?
Some conspiracy theorists think the US government has information on alien life and UFOs that they are withholding from the general population.
They think the Area 51 base - which was formally recognised in 2013 - holds captured aliens, their technology and crashed UFOs (unidentified flying objects) - something denied by the government.
Theories about the base started in 1989 when a man named Bob Lazar claimed in an interview on US TV that he was a physicist who had worked in Area 51.
He recently appeared on comedian Joe Rogan's podcast. There's also a Netflix documentary about him, which could have prompted renewed interest in his story.
Lazar said he had worked on taking apart a UFO and had read government documents describing alien involvement in life on earth.
He has no hard evidence or proof for what he's claiming, and no records of his alleged university physics degrees exist - but he definitely helped fuel the stories about Area 51.
As Thomas Bullard, author of The Myth and Mystery of UFOs says: "After trust between government and public eroded with Vietnam and Watergate, Roswell and Area 51 entered the popular vocabulary as bywords for official double-dealing."
Roswell is an area in New Mexico where an airborne object crashed in 1947.
The military says it was a weather balloon, but a theory has been widely held that it was actually a UFO that had crash-landed and then been covered up.
Despite the US government revealing in the 1990s that it was actually a nuclear test surveillance balloon, the incident still attracts lots of attention and conspiracy theories.
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