Update: With many now on the Reality Strikers, a new Special Unit has been formed to protect Earth, overseen by Megumi and her purse to make sure no threats hit them too hard, like the remnants of the Neo Reich. They are set up in London and are being housed in the Neo Big Ben as their base of operations.
Old: The Special Unit is located on Earth in Mega City, the capital of EarthGov. While it is part of the military, it's unit function is to investigate crimes and cases dealing with global threats around the world, as well as minor cases with superpowered enemies. The unit is led by Warren Carmichael, codenamed Ire. It is composed of various species that live on Earth, including reploids and even a Lunarian. Age groups don't seem to matter as much as the quality of service the person brings.
The Special Unit's building is located within a mansion next to the President's mansion. It's a two story mansion above ground, with two stories below ground, with multititudes of tunnels. With hidden areas and command centers and equipments, it's a fortress for combat against any foes who try to attack, with gardens and other areas for members to refine it as they see fit, with empty lots so each person can make their own personalized place. They also have teleporters directly to the Station.