The Castle was once a Goa'uld outpost, located on the planet PSX-394, which was at some time taken over by the Tau'ri of Stargate Command to become a prison colony which would house the Tau'ri's most dangerous prisoners who were considered to be too dangerous to be kept on Earth. Sometime after this, however, the Human inmates managed to stage a successful rebellion and took over The Castle, becoming the OP-CORE. After this event, the OP-CORE started running their own Stargate program from The Castle. (Stargate: "Worlds")
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