- Great Storm Chamber Library
- Eastern Entrance
- Main Tunnel
Occupation and Evacuation of the Librarians
Between the trilogies of Twig and Rook, the Librarians Academic - a union of earth and sky-scholars - were driven into the sewers by the Guardians of Night. Through the former's work however, the Librarians were able to construct a reasonable living area throughout the tunnels, and were responsible for the conversion of the main sewer chamber into the Great Storm Chamber Library. However, the living space still wasn't ideal: for instance, when it rained, water often leaked through the tunnels. The Librarians also set up a number of defences, such as giant crossbows. In addition to this, the Sewer Patrol was formed, designed to keep danger at bay - albeit, to their contemporaries they were viewed as fairly useless.
Later on, with the arrival of the Dark Maelstrom (to be instigated by Vox Verlix) immenent, the Librarians departed the sewers. Before doing so however, they fed false information to both General Tytugg of the Goblins, and Mother Muleclaw the Second of the Shrykes, which coaxed them into the Great Storm Chamber Library. The following events resulted in a huge battle between the goblins and shrykes and, with the simultaneous arrival of the storm, to the destruction of the sewers, and ultimately Undertown.
Entrances to the Sewers
On the eastern side of Undertown, entrance to the sewers could be accessed via a tall, curved obelisk behind a trough. On the obelisk was a circular, dark plaque, and pressing firmly on the plaque would enable entrance. For many years this secret was only known to the Librarians; beforehand, Goblins who had tried to enter the sewers would be greeted by a long plunge into a torrent of water which rushed towards a black tank, known as the Drowning Pool. The entrance was so narrow that most creatures could only walk through it single-file.
There wasn't a single, main western entrance, nevertheless various tunnels on the west wall of Undertown - which transported sewage into the Edgewater River - could be entered.