P3X-439 is an apparently uninhabited world of scattered forests and open fields, with an enormous crumbling monument of Ancient design that once resembled a person sitting on a throne. The colonnade of the monument contained writings in the Ancient language that spoke of a library of knowledge, or an Ancient repository. When SG-1 visited the planet, a repository of the Ancients materialized on the wall of the monument, and Anubis's fleet launched an attack to claim the device. O'Neill interfaced with the repository, accessing the knowledge of the Ancients, and SG-1 used C4 to destroy the device to prevent the technology from falling into the hands of Anubis.
Cross Reference: Ancients, Ancient Repository
Episode Reference: Lost City