The Military Base is located in the heart of Arizona and is no longer being used. The base was used as a 'successor', essentially, to the Project Sun-Streak research of the 70s and 80s.
The base was commissioned by the United States Government, specifically Military, to further research paranormal oddities and develop a 'ghost spy' of sorts: a spy that is able to infiltrate anything without the possibility of ever being detected.
Kate Heller and Professor Peter Richmond were both scientists at this facility during its operation. Heller was an 'Astral Traveller' before the accident that left her permanently, for the foreseeable future, separated from her physical body and her spirit trapped in the Astral plain. During the time following this, Heller's spirit fused with Richmond's body, much like what she has done with Lazarus Jones, leading to an exponential increase in progress for the facility.
There were specialist areas in the facility, one of which was dedicated to designing the Zero Bomb: a bomb designed to completely obliterate the ghosts rather than trapping them. The design is hinted at being incomplete but a final version is shown in the stage.
Another machine that had been developed in the facility was the Resurrection Machine that was used in the process of returning a spirit to its physical body; hence the name resurrection. It is stated the Heller played an integral role in the process of the machine but isn't described further how she is essential to its functionality.
Richmond fled the facility upon discovering that Sir William Hawksmoor had sent the government a holographic message detailing his demands. They were that in exchange for the body of Heller he would become the 'Knight Protector' to the Military. This led Richmond to take the body of Heller and hide elsewhere, which came to be Detroit where he changed his name to Professor Peter Brook and developed the Array and Digital Richmond in the basement of Montsaye High School; whilst also teaching at this location.