Kefka's Tower is an arena in Dissidia: Final Fantasy. It is the representative arena of Final Fantasy VI. It consists of several rails for grinding. It also contains breakable "Esper Pods".
In the Dynamic Version, the lower area spouts harmful gas at random(?) intervals. Each time the gas spouts, the Brave Pool increases by a small increment. Additionally, if a player is crashed into one of these walls, they will ricochet off and crash into the opposite facing wall. The damage dealt by these special walls is also added to the Brave Pool. Additionally, the damage dealt by the walls is not % based, meaning it's possible to break your opponents by ricocheting them.
In Final Fantasy VI, Kefka creates a tower from the ruins of Vector and the Magitek Facility. It is one of the places you have to go through to reach Kefka atop his tower.