The Aperture Science Testing Facility Theta-1653 was a Aperture Science facility build deep underground near the small Wisconsin town of Stanley to its' north. The facility was created at somepoint in 1924 Inio'zioni (1330 NE/1992 Golmar) following successful tests Aperture made in interuniversial portal technologies and built the a facility as a means to conduct further experiments into interuniversial travel and continuing the company's overarching portal research as well, albeit as a means to test the physics of the universe the site resided in compared to the homeuniverse.
Over time, Aperture began to see protentional for the site and planned on it being a nexus point for a vaste interconnected web of facilities in other universes but in 1938 Inio'zioni (1344 NE/2006 Golmar) the facility suddenly became isolated from the main center isolating many researchers and staff in the process, leaving the employees unaware of GLaDOS take over and Golmar Earth's chaos following the Black Mesa Incident and the six years of instability and destruction that ravaged the planet before being invaded and conquered by the Combine in the 7 Hour War. Intentionally, the employees just assumed it was some technical issue on the home universe end, as Aperture had been increasingly having technical problems beforehand, but as the hours turned to days, then to weeks, then to months, and finally a year, in 1939 Inio'zioni (1345 NE/2007 Golmar) the isolated staff began to realize something was wrong in the center as otherwise they would have been rescued by then. To further exasperate the issues was the dwindling food supplies in the facility by then that point was now being rationed and even then only had five years worth of supplies remaining. At first the administrators manage to keep the staff calm but as the food began to dwindle, so did any sense of peace as well. What security the facility had was quickly overwhelmed by the amount of desperate staff trying to gain access to the food supplies, eventually leading to violence to erupt with killings now occurring over access to the food supplies. By the next year, 1940 (1346 NE/2008 Golmar), what was suppose to last for five years, the food supplies were now gone complete and what staff survived now face the realization that they were now stuck in a isolated facility miles deep underground with no food and the slow and painful death by starvation. In face of such a fate, many chose to commit suicide then die slowly but a few chose to live, unable to kill themselves otherwise while others yet came to a horrific but desperate decision, cannibalism. What few of the original staff remained, was split between the cannibals and the non-cannibalism and as the fresh corpses of the staff that killed themselves began to dwindle, tensions between the two groups grew in turn until eventually the cannibals began to attack the non-cannibals. Although its' unknown what happened during this chaos what is known is that one of the researchers, Dr. Gideon Ikin, was the sole survivor, who documented the tragic events to the best of his abilities before he ultimately died from starvation, and wouldn't be discovered until the displaced Gaz and Dib Membrane and the Second Irken Empire Invader Zim and Tak discovered his skeleton 115 years later.
Since the chaotic and violent end of the facility's staff, the site remained undisturbed for decades, aided in part by how deep underground it was and its' secret nature. Then in 2041 Inio'zioni (1447 NE), a year after the conquest of Inio'zioni Earth by Axis forces, Combine forces began to search for the facility after discovering Aperture signature in the mid-west of the former US before discovery it miles deep underground outside of the now abandoned town of Stanley. For 10 years, the Combine would excavate the presumed location trying to find the site to gather as much information about the facility's research as they could before finally finding the site in late 2051 Inio'zioni (1457 NE) and wasted no time downloading all the files and abandoning the facility once more. It wasn't until 2055 Inio'zioni (1461 NE) when it had another group of visitors, the long lost children of Lucio Membrane, Gaz and Dib and the two former invaders Zim and Tak, who found themselves in the deeper parts of the facility at the same time, the last Tallest ruler of the Second Irken Empire, Kia, rediscovered the facility for his own ends, leading to conflict between the two groups resulting in Kia's death.
After this, the facility was abandoned once more until after the liberation of Inio'zioni Earth where the United Earth Federation turned over control of the area around the facility and later give it over to the Commonwealth of Golmaran States as a sign of good faith and allowing them to research the facility and discover what Aperture did in it so long ago.