The Library of Amarathia is a mystical place, created by the High Elves' most powerful mages in the city's glory days. The interior of the Library exists on another plane of existence to both Aelora and Terra, and is massive. It contains the entirety of Amarathia's magical knowledge, historical documentation and other forms of literature - including copies of most other texts produced by the other Aeloran nations. The Library's nature allows it to be near infinite in size, and yet the magics that flow through it make it easy to find the texts that are required. They have the convenient habit of being on whichever shelf you check first.
Sylvire has made the Library accessible from the Monastery in Terra as well as Amarathia itself, and it is heavily warded enough to stop all but the most powerful of enemies from entering it against her will. However, the Library was never designed with defense in mind, and so none of its many enchantments aside from Sylvire's own have defensive potential. The Library's main chamber is accompanied by several smaller rooms: the entrance hall, which Sylvire has converted into a bedroom, a storage room converted into a smaller bedroom for Aiedai, and staff offices that have been converted into a kitchen.