Visitors are descending on a remote Nevada desert near the secret U.S. military base known as Area 51.
No one knows exactly what to expect, but small towns near the once-secret military research site say they're preparing for the worst and hoping for the best.
Storm Area 51 started out as a Facebook event page with plans of raiding the military base.
It gained more than 2 million people interested in attending, but the event was eventually taken down from Facebook after military officials warned against it.
Now instead of a raid, more than 20,000 people are expected to attend this weekend's music festival in the small town of Rachel, Nevada.
Festival organizers say attendees are not interested in actually storming Area 51, but say thousands of alien enthusiasts are gathering to enjoy UFO stories, music, and culture.
It's been rumored that Area 51 housed government secrets about alien life.
The U.S. Air Force has issued warnings for people not to approach the gates of the Nevada Test and Training Range where Area 51 is located.