The Command Center or Headquarters are the center of military command structures, housing command interfaces and communication equipment as well as numerous uplinks to keep the battlefield data updated as often as possible. While the concept of military command center dates back to ancient times, modern command centers are quite different from those of old.
Both sides made extensive use of the newly introduced mobile command center, a halftrack vehicle with little armour, but powerful electronics to communicate with the forces on the battlefield. With the lack of any EVA interface, the Commanders had to rely on technicians and radio operators to communicate with the forces on the battlefield, which lowered effectiveness somewhat. Both also observed to have their own stasionary version (as seen in several mission and soviet ending in aftermath). The Soviets often defended their HQs with Tesla coils. Construction Yard or any standard building available may offer allowance for command purpose (oftenly emergency only).
The Soviets and the Allies, later Yuri has Construction Yards by deploying MCVs as their Command Centers. Another type of Command Center can be in the use of military leaders of both the Red Army and Allied Forces in which major city, like Moscow and Washington DC as their base of operations and Command Center. The Pentagon is a key Command Center for the Allies and the Soviet Union has the Kremlin as their own Command Center. Yuri's Lunar Command Center is seen during the Soviets' Moon mission. Yuri also have ancient themed and insanely armored castle as his "house" on Earth that became a Soviet target in their final battle.
In 1986, the Empire of the Rising Sun has their Construction Yard as the primary Command Center. The Imperial leaders, along with the Allied Coalition and USSR factions have the same Command Centers in different locations and e.g, Tokyo is home to the Empire's faction. Another type of this is a VIP Bunker for the safety of key Commanders and with some defenses around it. During To Tame a Living God, an Imperial Palace is a key Command Center for Emperor Yoshiro to which he was killed by the Red Army's speed of rushing on land. A Japanese themed castle also has been seen in Vladivostok as Prince Tatsu's command center. The Soviets still used the Kremlin, not only as main command center, but also as hidden cache for Soviet surprises such as Time machine and space shuttle launch site. An American secret base in Mt Rushmore can also be seen as Allied command center.
Years later, the advent of much more powerful processing systems and interfaces, most notably the EVA, allowed for complete reorganization of the command center design. Now the new interface was the primary method of commanding the military and allowed for an unprecedented level of precision. EVA was small and miniaturized, and could be manufactured in numbers. EVA interfaces were used by both GDI and Nod, and deployed on aircraft carriers, helicopter carriers, mobile command centers and inside the Temple of Nod.
GDI command centers were often aircraft and helicopters carriers but GDI's central HQ was classified (possibly Pentagon). The UN headquarters were in New York while Nod had a number of HQs globally. In 2002 the Sarajevo Temple, which was Kane's primary headquarters at that time, was destroyed by a GDI ion cannon.
With further refining of the technology, command centers were now located mostly on mobile platforms, such as the Montauk, Kodiak or the GDSS Philadelphia. Stationary command centers weren't completely phased out, but given the need for a commander's mobility, they were used less often by frontline commanders. Examples include the Nod Pyramid.
GDI's primary HQ was the GDSS Philadelphia a massive space station. Earth based GDI HQs could either be mobile or stationary. Nod had a variety of stationary command centers throughout the war, generally reserved for major commanders, like Hassan or Kane. Vega's Pyramid was an island-based command center, but it was destroyed by a nuclear missile because of Vega's failure.
The Forgotten, constructing their bases out of old, forgotten technology and civilian buildings, used waystations and old motels as command centers. They were guarded by old Mammoth Tanks and the most powerful of the Forgotten arsenal.
CABAL's core was a command center, and the source of the cyborg army. CABAL had a variety of fake cores, diverting GDI and Nod retaliation away from his true one. CABAL's central core, found only by intelligence sharing and collaboration between the two rival factions, was at the center of a massive base, with harvesting and manufacturing operations going on nearby. CABAL took no risks, and the base was defended by two special Obelisks, the super anti air Obelisk of Darkness and the super anti ground CABAL Obelisk, had a high-impenetrable Firestorm barrier, and the last line of defense was undoubtably the most powerful unit of the second war, the massive anti ground Core Defender that is weak to Orca Bombers.
In the Third Tiberium War, stationary command centers for GDI included three major nodes - the GDSS Philadelphia, the Pentagon and the Reykjavik military base, all of which were attacked in the opening stages of the Third Tiberium War by Nod, with only the Pentagon secured before it was overrun. GDI also constructed forward command posts to facilitate communications and command. Nod placed its bets in spreading out its command structure and make it decentralized, but still answering to Kane and the Inner Circle. This allowed for spreading misinformation and keeping GDI in the dark. Temple Prime, Nod's overall central command hub, was built over the ruins of the original Sarajevo Temple, and was also destroyed by an ion cannon. Following Temple Prime's destruction, Ayers Rock took over the CENTCOM role.
Mobile command centers were still in use (an example is the Huron), though some commanders preferred stationary command centers and camps (such as Ajay), as a stationary camp offered better connection to the military forces rather than a vehicle constantly on the move. Scrin Motherships are believed to be command centers for their Foremen, and had to be evacuated due to GDI's successful retaliation.
The Relay Node doubles as a Command Center, as it controls the entire Scrin force, giving them their Tiberium radiation. Its destruction will cause all Scrin units to degenerate, which the GDI Commander (TWIII) did.
Crawlers serve as mobile command centers. But speciallize vehicle like Metusalah are also extensively used, though not physically used in battle.