Repository of the Ancients

In the Stargate science fiction universe, the Repository of the Ancients is a device that contains a library of the knowledge of the Ancients, the builders of the Stargate system. The only part of the repository visible is the interface; whether there is a larger device behind it that supplies power or the actual information cannot be determined. The interface is a metallic circle, with a dark window in the middle. When activated, the device extrudes itself around the user's head, holding the head in place while the knowledge is transferred into their brain. The vast amount of knowledge the device transfers has a negative effect on species which cannot absorb all of the information; when Jack O'Neill used the device on two occasions, the information slowly took over his brain; while allowing him to build advanced technology, such as the power generator which allowed the Stargate to dial an eight-chevron address (The Fifth Race) and a weapon capable of defeating the Replicators (New Order), it also caused his brain to slowly degrade, rendering him unable to speak any language apart from Ancient. The Asgard have tried to transfer the data from the device into their own computer systems in order to try and learn from it; unfortunately, the amount of information is so vast that no system can handle it. However, when the Asgard transferred O'Neill's mind into the computer on Thor's ship, he was able to design the aforementioned anti-Replicator weapon before the information in his brain killed him. Only two repositories have been found; while there are concievably more, they would be a valuable asset to anyone who discovered them, due to the immense technological and scientific knowledge they contain.