An entire building has quietly vanished from the United States’ mysterious Area 51.
Before and after photographs of the top-secret military base in the Nevada desert show a large hangar has vanished.
The mystery around the site has sparked rumours aliens and UFO have been captured there, as American authorities reveal almost nothing publicly about what its purpose is.
Long-range photographs captured by private pilot Gabe Zeifman offer a rare insight into the layout of one of the most enigmatic landmarks in the world.
The pilot had permission to fly along the border of the base despite the airspace over Area 51 being tightly restricted.
He has flown over the area three times – enabling him to capture some curious changes at the site, according to The Sun.
In one of Mr Zeifman’s photos taken this April, a new hangar appears to be under construction at one part of the Area 51 site.
But just months later, the structure with a triangular sloped roof has vanished.
The second photo taken this July shows a void at the site where the perhaps temporary hangar once stood.
Zeifman, who is an air traffic controller records his flights with a GoPro camera, and can be heard in his footage asking permission to fly along the border of the Area 51 airspace.
He took the incredible photos of Area 51 and other top secret installations on the Nevada Test and Training Range after receiving permission to fly through the airspace.
He took the images while flying Cessna 150, after receiving permission from air traffic controllers to pass through the airspace last weekend because it was ‘cold’, meaning no military flights were taking place.
He told Mystery Wire that he has been incredibly careful during his flights not to cross the line into among the most heavily-restricted airspace in the world.
He told the publication passing into the airspace would land a pilot in serious trouble – although he added he did not think the consequences would be anything “dramatic like they’re going to shoot you down.”
In an April interview about the first time he flew over the airspace, Mr Zeifman said he saw nothing of interest as he passed by the site- but added that it was thrilling to have such a close encounter with one a famed mystery spot.
“I’m not really seeing any activity,” he said.
“It’s just the runways and stuff and I think it’s pretty cool anyway, just seeing that, you know, the place that everybody knows about, talks about, but you can’t really see.”
Only last year, thousands of alien fans plotted to ‘Storm Area 51.’
The September event saw hordes flock to the dusty patch of desert after an internet joke took on a life of its own.
The site has captured the popular imagination for decades, as extraterrestial conspiracy theories and science fiction added to its allure.
The site deep in the desert has signs dotted around the base warning deadly force is authorised against trespassers.
It wasn’t until 2013, that the CIA even acknowledged Area 51 existed.
Following a Freedom of Information request filed years earlier it confirmed the site did indeed exist, and is officially called ‘Groom Lake.’
Wild theories about what goes on behind the closely-guarded perimeter of Area 51 include that its a base for captured UFOs and alien remains.
Others speculate that the US government stores information about extraterrestrial activity at the base, and develops secret space-craft there based on alien technology.