In Marvel Comics' Terror on the Planet of the Apes, our fugitive heroes Jason, Alex and Malaguena encountered the knowledgeable old human Lightning Smith and his gibbon companion, Gilbert, who were seeking the Psychedrome, a legendary storehouse of artefacts located in the Forbidden Zone, so they could restore civilization.
Together, they found a village of peaceful, mountain-dwelling humans and apes, where Lightsmith finally located and accessed the Psychedrome, which turned out to be a vast alien spaceship which crashed on Earth and embedded deep within the mountain generations ago. It's alien inhabitants were the multi-eyed Keepers. They and their soldiers, a species of Winged Monkey-Demons either mutated or genetically bred from their distant relatives the primitive Assisimians ape tribe, were waiting patiently for a chance to gain control of the planet. Lightsmith was brought to their 'Conditioning Center' and brain-washed to be a "good person". Alex and Jason found the heart of the Psychedrome and an alien called the 'Keeper of the Light', then rescued Lightsmith. Following them into the craft, Brutus and his Mutant Drone allies discovered a silo full of missiles, lasers and other weapons. As apes, mutants and monkey-demons battled, Jason, Alex, Lightsmith, Gilbert and Malaguena escaped the complex, holding the Keeper at gunpoint. The Mutant Drones detonated the warheads, bringing down the mountain. Thinking the fortress destroyed, the surviving Keeper travelled with his captors. The Viking-styled North-Apes gave the company a Longship for their journey home, but made the Keeper stay against his will, believing him to be the Oracle promised in their religion. Deep under the mountain, the Psychedrome had not, in fact, been destroyed, and the Keepers began the slow task of rebuilding.
In the 2018 novel Death of the Planet of the Apes, Taylor also visits the Psychedrome. It is part of a longer adventure in a gleaming city inhabited by just one chimp-human boy - Messias - and his robot sentinels. Messias attributes Taylor's encounter with the ‘Keeper’ inside the spheroid auditorium to a radiation-induced hallucination, though he subsequently finds himself fighting creatures similar to the winged monkey-demons. The entire city disappears upon Messias' death, suggesting that it was entirely an illusion.