Kayon

Prime cartoon
Kaon was the Decepticon capital on Cybertron. When Bumblebee used a cortical psychic patch to enter Megatron's subconscious, he found himself in a recreation of the city. Sick Mind Attempting to find Vector Sigma, Jack Darby and Arcee were led to Kaon by the Key to Vector Sigma. Orion Pax, Part 2 They managed to wake up an Insecticon sentry which attacked Arcee while Jack went below ground to the Vector Sigma chamber. He was able to download the contents of the Matrix from the computer, despite interference from scraplets, and he and Arcee headed back for the space bridge. Orion Pax, Part 3 Megatron honed his gladiator skills in "the pits of Kaon". Crossfire

[http://tfwiki.net/wiki/Image:SickMind-Kaon.jpg ]

[edit] Exodus novel
Built on a plateau three times the size of Iacon, Kaon was the industrial heart of Cybertron, where nameless members of the lowcastes toiled endlessly. It was a dark, smoking mess of a city that was impossible to navigate without the Communication Grid. TheHigh Council ignored the emerging gladiatorial combat in the areas surrounding Kaon, acknowledging it was the inhabitants' only escape in their lives. A champion taking the name Megatronus emerged. This Megatron took control of the gladiators and formed theDecepticons. His base was a single, large pyramid.

During the war, Optimus Prime, Jazz and Prowl rescued Sentinel Prime from the pyramid, which had become Kaon Prison. Megatron and Shockwave had made a deal with the Underworlders to chain the prisoners underground. The Autobots were only confronted by two gibbering guards, which Optimus presumed was the toll of Dark Energon. Transformers: Exodus