Skynet Core is the facility housing the Skynet's main frame.
As Skynet was originally built by Cyberdyne Systems Corporation for Strategic Air Command - North American Air Defense (SAC-NORAD), the Skynet Core is located in Cheyenne Mountain, Colorado, the base of SAC-NORAD, which is the world's most heavily-armored and defended mountain. Hollowed out, reinforced and armored, Cheyenne Mountain is capable of withstanding a direct hit from a nuclear missile. This made it the perfect installation at which to build Skynet's mainframe. At some point during the war, after Skynet had launched its missiles, Skynet had the mountain around it destroyed, leaving a cold, gleaming structure as a display of the supremacy of the machines.
Heavily-armored and fortified, Skynet's Central Core Installation at Cheyenne Mountain was guarded around the clock by squads of Series 800 Terminators with patrols of Aerial Hunter Killers and Hunter Killer Tanks, and was defended from large scale rebel assaults by massive Phased Plasma Cannons.
Skynet's Central Core was located deep underground within Skynet's main complex. From intercepted surveillance of video data feed, the Resistance was able to hypothesize that this Central Core was a form of cold fusion reactor, needed to supply Skynet with its tremendous energy requirements. This Central Core is the key to Skynet's ability to operate; Skynet would be rendered virtually disabled without it. It has therefore become the main target for the most skilled Resistance strike teams. The Central Core is protected by the T-1000000, and thus there have, as of yet, been no successful strikes against it.
As well as the Cheyenne Mountain Complex, Skynet has another major installation two-thousand feet beneath Navajo Mountain near the Continental Divide west of Colorado Springs. This is a center for machine activity and Skynet control, and as such has also been a target of many Resistance attacks.
In The Terminator: Dawn of Fate, the Resistance invades Cheyenne Mountain in order to destroy Skynet's Central Processor. Kyle Reese is instrumental in destroying the primary processor core despite heavy opposition from attacking Skynet units. Before its destruction, Skynet is able to contact an orbiting satellite and activates a fail-safe which restores Skynet at a new location (presumably the Los Angeles base).
In Terminator 3: Rise of the Machines timeline, a combination of more-advanced computer technology and other differences that led to Skynet's creation resulted in it being developed as a distributed network: Skynet now existed "on the Internet", without one central data core or primary set of servers. Originally, Skynet may have been limited to multiple Cyber Research Systems development servers, but after spreading itself like a virus through the Internet, its program was spread out across every major computer server or network, "in office buildings, dorm rooms, everywhere". This made it physically impossible for a single surgical strike to destroy it on Judgment Day.
In Terminator Salvation timeline, Skynet had an on-surface base in the ruins of San Francisco, which housed an interface with Skynet and a Terminator Factory. The site had been rendered almost inaccessible due to the partial destruction of the Golden Gate Bridge and only air units or those who could move along the remaining support links of the bridge could enter the city. This installation was destroyed during a Resistance's operation in 2018.
- T2 3-D: Battle Across Time (First appearance)
- The Terminator: Dawn of Fate
- Terminator Genisys (Mentioned only)
- Terminator Genisys: Revolution
- Terminator: Resistance
- ↑ However, due to the advanced complex design and limited self-awareness and Skynet's fear of the T-1000000 becoming independent of its creator, there is no verifiable evidence that the T-1000000 ever came into existence prior to its sending back the Terminators to eliminate John Connor and its destruction at the hands of the Resistance.