Library of the Ancient scientist and legendary "Wizard" Merlin, located in the village of Camelot on an alien world. Merlin lived among the people many centuries ago, during the era of the legendary Arthur and his Knights of the Round Table -- and Camelot served as their point of departure in the search for the Holy Grail. Merlin's library is thus a dusty treasure trove of information and technology developed by the Ancient after he ascended to a higher plane and then eventually retook mortal, human form.
When SG-1 arrived on the planet in search of information on Merlin's anti-Ori weapon they learned that the library has remained sealed for the generations since his departure -- largely because the local people regarded him suspiciously as a "Wizard of darkness." After convincing Antonius to unlock the seal, the team found the library to be protected by a Black Knight -- a menacing, holographic warrior who appeared in the village.
Inside the library the team found an Ancient control pedestal (which controlled the Black Knight) and a holographic projection of Merlin himself. After his message pointed them to the Sangraal, Meurik informed them of the legend that Arthur and his knights went searching for the jewel in three distant lands: Castiana, Sahal, and Vagonbrei.
Camelot - Merlin's library is unsealed after many centuries when SG-1 arrives in Camelot in search of information on the Ancient's anti-Ori weapon.
Insiders - SG-1 reports to General Landry that Daniel has returned to Merlin's library, but so far hasn't dug up any new information on the Sangraal's location.