Mirrored Library (Planescape)
The Mirrored Library, Timaresh, was one of the last great creations of the kamerel empire in its waning days. Crafted by Hallonac, one of the kind's premiere mirror mages, it was first spawned from the deep-seated xenophobia that struck throughout the empire in its decline. This building and its contents were originally intended as a way of spying on the affairs of other peoples from afar, that they could be protected from the designs of others. By weaving together subtle mirror magics in never-before-seen ways, Hallonac managed to form a self-perpetuating (as opposed to permanent) enchantment that could read and reproduce every written work written throughout the planes within the confines of the first ring of the Outlands. Further, beneath her Bindery, as she called it, was constructed an infinite repository through self-reflected extradimensional mirrors to hold these innumerous tomes as they were produced.
Unfortunately, others of her kind failed to see the genius of her creation, instead seeing it as nothing but an infection on their then-secluded way of life by the outside world. Hallonac was slaughtered in disgust for her crimes against kamerel. Unfortunately, her creation was too well-made to be destroyed, the best efforts of the kamerel in vein as its self-perpetuating mending spells healed whatever damage they tried to inflict. Thus, they simply boarded up the building, declaring it Timaresh: in their tongue, the Collection of Hated Lore.
The Library continued to produce its works over the decades to come, and to the kamerel it passed into obscurity, none daring to even step foot within its walls. When the kamerel fell and the rilmani claimed their lands for their own, they found the building and took it for their own, using its products to learn more of all and applying the knowledge within to better serve the balance. Even amongst those few allowed into Sum Of All, none are allowed within its walls but for the rilmani itself.