Moonbase One was the first Moon base built after the Decepticons' conquest of Cybertron. It appears to have been primarily a command base, and many Autobots were stationed here, including Optimus Prime, Ratchet, Ironhide, Prowl, Brawn, and the Dinobots, but only Jazz and Cliffjumper were left behind when Optimus Prime went to provide reinforcements to Autobot City. The only thing of any note that ever happened to it was getting eaten by Unicron. Moonbase Two is (well, was) its neighbor (until both of them got eaten). For a while, it spent time being slowly digested within Unicron's bowels, at least until he was obliterated by a mystical glowing thingy.