Metru Nui (OU)

"This was once a great city, the brain of a Great Spirit. Now it is gone, sacrificed to Blackout's ambitions."

- Orion Pax

Metru Nui, also known as the City of Legends, was an island city in the Matoran Universe that functioned as the brain of the Great Spirit Mata Nui. It was located inside the head of the Great Spirit Robot in the northernmost part of the Matoran Universe and was maintained by a large population of Matoran workers. Due to its strategic significance to the Matoran Universe as a whole, it was coveted by the Vrai in the Vrai War and the Brotherhood of Makuta and Dark Hunters in later conflicts, but was consistently protected by both local and foreign heroes, including at one point the Toa Metru.

In 100,080 CMT, all structures on the surface of Metru Nui were dismantled and the materials were used to build Darkmount. Its Matoran were then evacuated onto Darkmount to escape the death of Mata Nui.

Description
Like almost everything else in the Matoran Universe, Metru Nui was constructed entirely out of different forms of protodermis. It was a mechanical metropolis that was primarily split into six districts, each of which corresponded to one of the elements of the native Matoran population: Fire, Water, Ice, Earth, Stone, and Air. Each district was connected by a system of transportation chutes which could be used to quickly travel to other parts of the city.

Known districts of Metru Nui were Ta-Metru, the industrialized district of Fire that produced weapons, tools, and other necessities; Ga-Metru, the district of Water that contained spiritual and education centers; Ko-Metru, the district of Ice that was home to gigantic libraries; and Le-Metru, the home of the island's transportation chute system and airship factories. Other landmarks included the Coliseum, a gigantic cone-shaped building at the center of Metru Nui that contained an arena where Matoran in the city would gather for special events and announcements.

Metru Nui was reduced to a barren and uninhabited landscape when Blackout brainwashed the Matoran into dismantling every building on its surface and used the materials to build Darkmount.

Early History
The Great Beings designed Metru Nui as the brain of the Great Spirit Mata Nui and laid its foundations inside the head of the Great Spirit Robot while the Matoran constructed the city on top according to their specifications.

In 625 CMT, the Vrai invaded the Matoran Universe with the intention to seize control of the Mata Nui robot and turn it against the Great Beings. The Vrai entered Mata Nui from the south and fought their way upwards towards the north of the Matoran Universe in order to conquer Metru Nui, the brain and core processor of the robot, and assume direct control. An alliance of Matoran Universe inhabitants fought against the Vrai invaders, but were unable to stop them from advancing north. Miserix, the leader of the alliance, feared that the Vrai would take Metru Nui, but Angonce reassured him that the Great Beings had a secret weapon: the Elite Makuta.

The Vrai established an airfield in the Protodermis Sea around Metru Nui that would enable them to bombard it from the air. Miserix ordered the newly-created Elite Makuta to destroy this airfield. The Elite Makuta not only succeeded in this mission, but were also able to completely drive the invading Vrai out of the Matoran Universe over the next two years.

Mid-History
In 20,576 CMT, a Ta-Matoran named Kakamu was created aboard the Red Star and teleported down to an education center in Ga-Metru to be assimilated into the city. The main protector of Metru Nui at the time, Toa Helryx, welcomed the new Matoran to Metru Nui and introduced them to the school, where they would learn more about the city and be able to choose an occupation in the district of their element at the end of their schooling. Kakamu was disinterested in the schooling, but completed it nonetheless and chose to become a mask maker in Ta-Metru.

In 20,580 CMT, the Matoran Civil War broke out across Metru Nui and Kakamu was drafted into it on the side of the Ta-Matoran. One day, Kakamu was fighting alongside his platoon in Ga-Metru when its protodermis banks flooded and he was swept out to sea. A lightning bolt from the Red Star then struck him in the water and transformed him into a Toa of Fire. The disoriented and confused Kakamu washed up on the shores of Daxia and was recruited into the Order of Mata Nui.

At some point over the next few thousand years, Kakamu was sent back to Metru Nui to investigate an anonymous tip-off that claimed that the Dark Hunters had attached a bomb to a chute in Le-Metru. This "bomb" was in fact a Genetic Manipulator, which extracted a genetic sample from Kakamu when he examined it and appeared to power down. Kakamu assumed that the threat had been neutralized, so he handed the device over to the Matoran, who placed it in a storage closet somewhere in the city. However, neither party was aware that the device was still running and creating a clone of Kakamu inside. Eventually, Trantoshen emerged from the device and left Metru Nui.

In 96,080 CMT, robotic order-enforcers named Vahki were created to patrol the streets and uphold the law on Metru Nui.

The Last Days
In 99,080 CMT, the Quest for the Master Sword was announced. Makuta Blackout and Zev Raregroove worked together to find the sword, which was located beneath a temple on Metru Nui, and defeat its guardians. Team ToaLewa31 also attempted to find the sword, but failed because Blackout and Zev were much more active in their search. Once Blackout and Zev had found the Sword, it was taken to the Coliseum, where Turaga Dume gave a speech and handed out medals to the participants in the quest. However, Blackout took this moment to steal the Master Sword and betray Zev. It was around this time when the Toa Metru came into existence and Makuta Teridax infected the core processor beneath Metru Nui with a virus that cast Mata Nui into a deep sleep.

In 100,079 CMT, Blackout had image manipulator chips inserted into all the telescreens of Metru Nui. These chips were used to display subliminal messages in the transmission feed that convinced the Matoran populace to kill Turaga Dume. With Dume dead, Malygos spread persuasion particles across the city that brainwashed the Matoran into accepting him as the new Turaga. Turaga Malygos sent some of the Vahki that were now under his control to kill Jarr when the Zyglak mercenary threatened to destroy Xia unless he received protosteel, but Jarr destroyed these Vahki and escaped. It was around this time that Blackout sent a group of Corrupted Toa to protect Metru Nui for an unknown reason.

Malygos's conquest of Metru Nui elevated him to the status of one of the five most prominent rulers of the Matoran Universe. The Five Kings Treaty was then drawn up and signed by these five rulers to prevent any of them from expanding their territory under the threat of immediate retaliation. This treaty prevented Blackout from advancing his plan to take over the Matoran Universe, so he tried to gain power with the Icarus satellite weapon, but it was rendered useless when Malygos forced Blackout to share control of it also. Blackout then realized that he had no choice but to use the Vahi Cube to rewind time by six months for his plan to succeed. The Five Kings Treaty was erased from existence, but Malygos remained the Turaga of Metru Nui. Blackout sent some Corrupted Toa to guard Malygos, but he turned down the offer.

In 100,080 CMT, Blackout conquered the Matoran Universe by using the Theta Gate to summon the Legion of the Eclipse: an infinite army of Rahkshi, robots, Rahi, demons, and wraiths. However, his reign was short-lived: Blackout soon discovered that the bearer of the Matoran Universe, the Great Spirit Mata Nui, was dying, which would lead to the Matoran Universe becoming uninhabitable. Determined to escape the apocalypse, Blackout used persuasion particles to convince the Matoran to disassemble every building on Metru Nui and use the materials to build Darkmount, a replica of Atlantis, that would enable them to survive the death of Mata Nui. Once Darkmount was completed, Blackout transported the Matoran of Metru Nui aboard (as well as countless other Matoran Universe populations) and took to the stars.

Because the island of Mata Nui had previously been destroyed, Metru Nui floated up from the dead Matoran Universe to take its place on the surface of Aqua Magna.

Modern Era
In 150,082 CMT, Orion Pax assembled a fleet of Great Being-allied boats and airships on the barren surface of Metru Nui in preparation for an attack on Shinobi-Nui. Once the army was ready, Orion Pax led the fleet in the Battle of Shinobi-Nui.