Massive star bases made up of dozens of station parts totaling to multimillion tonned structures. All being modular of course so no two stations would need to be the same. One station would be geared toward being a fleet base so they would have repair yards (hangars), maintenance modules, recreation facilities, logistics, ect. Another on the border with another empire would be for defense, so more weapons/ammo, sensors, mined, ect. Each would defiantly have a station core (several bridges, flag bridges, and sensors), at least one weapons bay (size dependent on the game), ground factory, and at least enough maintenance modules to support the weapons bays.