The Konoha Archive Library (木ノ葉古書所, Konoha Toshodokoro, literally meaning: Leaf Ancient Book Place) is located within the Hokage Monument. Information on its ninja, past and current, is stored there, as well as other points of interest such as Akatsuki as well as other sensitive village information.
Because it is located on the Hokage Monument, it was one of the few buildings to survive the Invasion of Pain.