The Base is an area only exclusive to both teams. It has a wide selection of spawners, but not the Tracker and MAC Tank. There are 6 spawns.
Underground - The location is obviously, underground, however it could be used to sneak secretly into the enemies base. It only spawns the ATV
2nd Floor (Ground Vehicle Station) - This is the floor where you can spawn the Battle Tank, Artillery, Jeep, ATV, and the Spawn Truck.
3rd Floor (Flying Vehicle Station) - This is the floor where you can spawn the Shadow Fighter, Vortex Fighter, and Bomber.
Top of Base (Anti-Aircraft Turret) - This is the floor where you can spawn the Anti-Air Turrets and Anti-Vehicle Turrets.
Dock (Navy Station) - This is the area where you can spawn the Destroyer, SpeedBoat, and the Submarine.
Side Wing - An area that is on the left/right side of the base. It also has the Anti-Personnel Turret and Attack Helicopter.
More information can also be found on the Locations page