Coliseum

The Coliseum was the main structure on Metru Nui, located in the center of the city. It was where Turaga Dume resided, and the location where sports were played. During the fall of Metru Nui, Teridax used its vast basement to store the Matoran in his plan to take control of the Matoran.

History
It is unknown who built it and for what purpose. But whatever the case, the Turaga called Dume and the Turaga who ruled before him always used it as their residence and place to govern the city from. In the Toa/Dark Hunter War, the Toa used it as their Headquarters, sending the Toa on missions from there. After the Toa won the war, sporting events resumed.

During the rise of Teridax, he used it to store the Matoran in its basement. The Toa Metru saved six, but vowed to return and rescue the others. During their absence, Sidorak and Roodaka took over the Coliseum and made it the Visorak base (under the orders of Teridax). The Toa Hordika, aided by the Rahaga, saved the Matoran and defeated the Visorak hordes. This Toa victory was known as the Final Battle for Metru Nui. The battle of Metru Nui was the battle where Sidorak was killed by Keetongu.

The Toa and Matoran left the city for Mata Nui, but when they returned, it was rebuilt.

After Teridax took over the universe he appointed Ahkmou as "Turaga" of Metru Nui and imprisoned the other Turaga in chambers in the Coliseum.

After Teridax's death the Coliseum was heavly damaged and it was again abandoned along with the rest of the Matoran Universe.

Important Features

 * The Sea of Protodermis
 * The gigantic basement that was used to store the Matoran Spheres during the Great Cataclysm.
 * The balcony on which Dume, the Rahaga, and Keetongu resided when they were rebuilding Metru Nui.
 * Dume's Box
 * Dume's Throne Room
 * Sundial Room
 * Power Plant

Trivia

 * After Matoro sacrificed himself for Mata Nui, a ceremony for him in which every Matoran joined was held in the Coliseum.
 * As said in Dwellers in the Darkness, there is some place far below the ground, which Teridax attempted to reach. It is said that the only way to enter this mysterious place is by destroying the Coliseum´s foundation. This is thought to be Mata Nui's Brain.
 * It is known that the Coliseum cracking is a result of Mata Nui's life being in danger. It has since stopped after Matoro saved his life.
 * It is believed that the Coliseum has been home to Naming Day ceremonies.