The 4 Champions' Arena:
The Four Champion's Arena was built for the specific purpose of hosting the 1st Shinobi World Tournament, where competitors will fight each other to be crowned to the best shinobi in the world. It is a circular arena, the fighting stage is a a 300 meters diameter circle composed of sand, dirt, sweat and the pride of defeated opponents. The spectators' area is composed of three levels, each one higher than the one below it. It has a capacity for tens of thousands of people. Very complex Fuuinjutsu has been applied to protect the spectator's area, with three invisible barriers of X-rank strength preventing jutsus and other attacks from harming the audience and allowing the fighters the opportunity to go all out. The barrier is circular, placed on the limits of the arena and rises up to 10,000 meters above it. Because this barrier is extremely expensive and taxing (requiring several shinobi to maintain) it is only active during the duration of the event.