Council Citadel

Standing above its surroundings in the capital city of Cybertron, the Council Citadel served as the meeting place for the High Council of Maximal Elders.

Fiction

Beast Machines cartoon

After "purifying" Cybertron, Megatron made it his base of operations, turning the meeting room into his throne room. Master of the House

It was also where he originally kept the sparks of the kidnapped Transformers. Fires of the Past

During the Vehicons' assault on the big floating head, it crashed into the Citadel after losing all its power, but without damaging the Citadel itself. The Citadel was destroyed by Megatron, tunneling through to the planet's core to reach the Technoganic liquid. Endgame Pt. I: The Downward Spiral