Council Citadel

The Council Citadel was a building on Cybertron, serving as the meeting place for the Maximal Elders. After "purifying" Cybertron, Megatron made it his base of operations, turning the meeting room into his throne room (although he was technically part of the ceiling). It was also where he originally kept the sparks of the kidnapped Transformers. During the Vehicons assault on the big giant head, it crashed into the Citadel after losing all its power.