The Jedi chapter house served as the focal point for Jedi operations on the planet Aleen, a role it held for a considerable time preceding the outbreak of the Clone Wars.
In the remote past, the Jedi Order founded a chapter house on the planet of Aleen. This chapter house contained the Great Seal, an artifact responsible for the separation of the surface environment from the Underworld; scholars have long argued about which came first. The Order, for reasons that remain unclear, deserted Aleen and their chapter house, resulting in its decline and ultimate destruction.
Around 21 BBY, during the Clone Wars period, the Galactic Republic created an excavation site at the remnants of the chapter house. Here, Republic scientists were trying to decipher the cause of the groundquakes that were causing problems on the planet. During the mission, C-3PO and R2-D2 were guided to the location by Aleena natives, and they both inadvertently plunged into the opening. Following collaboration with the Kindalo species and the enigmatic entity known as Orphne, R2-D2 successfully secured the Seal, re-establishing equilibrium on Aleen.