Finn and Jake first use the Library while searching for knowledge in the episode "The Real You" but are forced to leave when they make too much noise. The Library is run by Turtle Princess. There is a secret area in the Library, which is the Moldos' Secret Lair.
Finn is in the Library during his dream in "King Worm" for a short while as the third place he is transported to at the beginning of the episode.
Turtle Princess' room
At the uppermost tower of the Library is a room in which Turtle Princess sleeps and spends time. It is unknown whether she has her own kingdom or whether the library is her domain.
In "Princess Monster Wife," Turtle Princess' bedroom can be seen.
- Some of the chairs are decorated with an owl, a symbol of knowledge.
- Some of the books seem to be organized by rhyme, such as the "-itties" shelf.
- The Library seems to be the remains of an old building buried in the ground suggesting its Pre-War origins.