Setting

"The arena consists of a ruined Blitzball stadium surrounding a circular platform over a field of lava, which is treated as a Banish Trap. A massive replica of Jecht's sword appears on the central platform, much like after defeating Braska's Final Aeon in the original game. Long grind bars run along the outer edge of the arena, connecting the central platform to the ruined "stands" on the opposite side."
(As stated in the wiki.)