Cho-Koro is the seventh Koro on the island of Mata Nui and home to all Chosen Ones.
In The Rise and Fall of the Toa, Cho-Koro is a megacity constructed after the Matoran migrated to Mata Nui. It is divided into many quarters, surrounding the Tower of Ages, where Turaga JTB, Turaga of Cho-Koro, oversees the Matoran. The city lie on a small island in the Papa Niho Archipelago.
Inside the tower, there is a machine which can grant the city the power of a Kanohi mask. Mostly, a Huna is used, to keep the city hidden.
After the Chosen Ones migrated to Mata Nui, Cho-Koro was built under the guidance of Turaga JTB, who became the city's leader after it was finished. After many years of peace, the Toa came to Cho-Koro in search of the Kanohi masks. The city survived the Makuta Wars very well and only participated in the battle of Kini-Nui, by sending Omega Warriors and an Agetngarahk. During the Bohrok Wars, the city was attacked and destroyed by a swarm of Lehvak, who were only able to breach the city's line of defense because Takaku sabotaged the Mask Machine. The inhabitants managed too flee on the sea, leaving their destroyed home back. What happened then is unknown.
In MoH, the city lies, in contrary to TRAFOTT, on the most southern tip of the island Mata Nui. It is not as high advanced as in TRAFOTT, and has a Ga-Koro-like appearance. It is ruled by a Turaga council, led by Turaga Dimensioneer. During the Bohrok Wars, it was heavily damaged by the Swarm Commandos.
It should be noted that the city is called BZ-Koro in Mask of Humor.
In KoC the city is high-tech again, but in the south of the island. Not much is known about this incarnation about the city, not even the identity of its Turaga.