Star Forge
From the Encyclopedia of Speculative Fiction - http://encyclopedia.wizards.pro
As an artifact of the Dark Side, the Star Forge corrupted those who used it, feeding its desire for death. Ajunta Pall hinted that it may have been known, and used by, the earliest Sith. After the Mandalorian Wars, it came into the service of Darth Revan and Darth Malak, who had been powerful and honorable Jedi Knights until discovering the Star Maps leading to the location of the ancient space station.
The scale of the Star Forge was extraordinary for its time. Capital ships could easily move between the gaps of the three "fins" that radiated outwards from the central spherical structure. While having few apparent docks for capital ships, millions of fighter craft and smaller freighters were able to dock at bays located on each of the three "fins".
Externally, the Star Forge possessed little defensive weaponry save for several turbolasers near its hangar bays, instead relying entirely on its massive ship production capability as a means to defend itself. Internally, it was capable of manufacturing droids for defence, coupled with heavy blast doors that ran throughout the entire facility.
As was the case with all apparent products of Rakatan engineering, the Star Forge managed to survive several tens of thousands of years idling and without an operational crew by relying on its built-in automated repair systems.
It was destroyed at the end of the Jedi Civil War (3,956 BBY), by a Republic fleet bolstered by the Battle Meditation of Bastila Shan.
Trivia
The Sith Lord Ajunta Pall, whose spirit Revan encountered on Korriban, gave several hints that the early Sith Lords had access to a Star Map (This map received Dark Side power from the Star Forge), which apparently enhanced their powers.