The Library is the primary information repository in The City.
The Library is an enormous building, with rows upon rows of bookshelves reaching its ceiling. It houses a vast array of multimedia, from books to internet databases, apparently containing "all of human knowledge." Library patrons check out books via retinal scan identification, which is overseen by the excessively cheerful librarian; if anyone trying to check out is found by the retinal scan to be in possession of overdue library items, then they are promptly detained by a forcefield and their retinas are confiscated. There is also a snack machine.
When GIR was locked into "duty mode" by Zim, he ultimately decided that information about Earth could best be found in the Library; equipping himself with an information-gathering container, the brutally efficient robot broke down the doors of the establishment and demanded that the librarian give him access to all knowledge of humanity. Displeased with her reply ("That'd be under Reference!"), GIR promptly deployed one of the data canister's many tentacle-like information-gathering cables, which latched onto the librarian's brain and harvested the information in her brain. He proceeded to do this to all of the Library's patrons and computers until Zim confronted him, which prompted GIR to attempt to kill his erstwhile master.