After the Luminoth were defeated by the Ing in Agon Wastes, Torvus Bog, and Sanctuary Fortress, they fled here and placed themselves in stasis, with U-Mos staying awake as the Sentinel. From here, he guides Samus on her quest to retrieve the stolen Light of Aether.
Shortly after Samus enters the Great Temple, she is attacked in the Temple Sanctuary by a large number of Splinters and the Alpha Splinter, which is quickly possessed by an Ing trying to take the energy from Aether's last Energy Controller. When it is defeated it relinquishes the Energy Transfer Module, which bonds to her Varia Suit and ultimately ties her to the conflict engulfing the planet. Other enemies she encounters in this area include Sandbats in Transport A Access, Lightflyers in Transport B Access, and a duo of Harmony Class Drones in Transport C Access.
The Great Temple serves as a hub by which the major areas of the Temple Grounds can be accessed with ease, and by extension the three regions of Aether. Samus returns here often to receive guidance from U-Mos and gain entrance to previously unexplored areas of the planet.
- "Aether was a fertile, aged world with bountiful fields and oceans. The native creatures were gentle compared to the other worlds we had encountered. We settled in a mountain region first, in cliffside dwellings. In time, we established settlements in the green forest of Torvus and in the fertile plains of Agon. A Great Temple was built between our three domains, a place of peace and a monument to our accomplishments. It was a time of harmony for our people. " —Luminoth Lore (Metroid Prime 2: Echoes)
- "What few remained gathered in the Great Temple. There, all but U-Mos, the last Sentinel of Aether, entered into life-preserving stasis. There they remain, to be released once the Ing were destroyed...or to sleep forever. His people safe, U-Mos prepared for the last, terrible assault. In the silence of the Great Temple, he prayed for salvation, for deliverance from the terror of the Ing." —Luminoth Lore (Metroid Prime 2: Echoes)
- "System Alert. Unknown item acquired. Alien technology has bonded to armor systems. Threat scan complete. No negative impact on suit performance." —Acquisition Data (Metroid Prime 2: Echoes)