In the Marathon trilogy of games, Lh'owon is the homeworld of the cybernetic S'pht. It is located in the galactic core and is unreachable from human space except by a ship with FTL capability.
Over a thousand years before Marathon takes place, Lh'owon was found by the Pfhor and all the S'pht on the planet were enslaved. The S'pht computers and the knowledge they contained about their race's history remained, due to the Pfhor's ignorance, and was advanced enough to continue functioning for over a thousand years until Durandal returned with his ship full of liberated S'pht.