The lair itself was at the utmost top of a dangerous staircase and was shrouded in shadow and darkness. The tunnel walls themselves were smooth, as if worn by immeasurable touching. It was wide enough for Frodo and Sam to walk side by side with their outstretched hands touching the side walls. Inside were the skeletons and rotting corpses of Shelob's past prey; deeper into the cave could be found sticky, innumberable webs in a vast maze of tunnels. One path led to the Tower of Cirith Ungol, which was blocked by a half-door to keep Shelob out. Other paths led to various other places, most of which were only known by Shelob herself. There is also a foul and evil smell in the air, sensed by Frodo and Sam.
In this place, Shelob had free rein to do whatever she wished, including devouring the unwitting inhabitants of the Tower of Cirith Ungol; this freedom is allotted by the Dark Lord Sauron in return for her services. During the quest to destroy the One Ring, Frodo and Sam were tricked by Gollum to venture here in order to cross into Mordor and only through use of the Phial of Galadriel are they able to venture out. Shelob, using one of her many tunnels, sneaks out and stings Frodo with the intent to eat him at a later time. However, Sam finds them and fights off Shelob using the Phial of Galadriel and Sting, and manages to wound her in the abdomen. Shelob slinks back to her cave and her fate is unknown, though she may have died of her injuries.
In Sindarin, ungol is a word for "spider."