It has a Shooting gallery, which Pierce Carradine controls and assists in Aya Brea's training sessions. There's a Firearms Control room where Aya can talk to Jodie Bouquet and use BP. There's also a parking lot garage with a save point. Baldwin's Office is located, here.
Aya's and Pierce's vehicles are located here. Aya's trunk becomes available during her 2nd time at MIST HQ. There is a save point at the far end of the room and a Recovery 3 behind Pierce's vehicle (both times). The Firearms Control room and Bouquet's Guns and Ammo shop are available for purchasing items and picking up Shooting gallery prizes.
Not officially named, but given it's own room ID#, this location is used for the post-Akropolis Tower cutscene where Aya is given her next orders.