Metru Nui

"Our island home... refound."

- Turaga Vakama upon the rediscovery of Metru Nui

Metru Nui, the City of Legends, was the island that formed Mata Nui's brain. It was inhabited by 1000 Matoran up until around 100,000 years after the creation of the universe, at which time new Matoran from other locations moved in when their homes were destroyed. The location was key to the health of Mata Nui, and if the Matoran of the city stopped working, Mata Nui would fall ill and slowly begin to die. It was found directly beneath Mata Nui, in the middle of the Silver Sea. Metru Nui and its troubles are key to the central plot of the Bionicle.

History
The city of Metru Nui was founded and built roughly a hundred thousand years ago, around the same time that the Brotherhood of Makuta and Order of Mata Nui were founded. Metru Nui's foundations were laid by the Great Beings, and the rest was built by Matoran. It is also known that Helryx was somehow involved in this. Since then, it has been the ecumenopolis homeland of the Matoran for millenia.

Around eighty thousand years ago, a dispute between Ta-Matoran and Po-Matoran, regarding boundaries and trade evolved in to a civil war in which Ga-Matoran, Onu-Matoran and Ta-Matoran fought against Le-Matoran, Ko-Matoran and Po-Matoran. This civil war caused the "Great Disruption", an event that weakened the Great Spirit. Little else is known about the four-hundred-year conflict, but the Brotherhood of Makuta ended the fighting and banished the war leaders to a place known as "The Pit". The Order of Mata Nui placed an agent in the city to ward off further conflicts.

Metru Nui was definitely not devoid of conflict after the war, however. 1300 years ago, Teridax infected the Great Spirit with a virus that caused Mata Nui to gradually lose consciousness. 300 years later, the Brotherhood of Makuta set in motion a plan to overthrow Mata Nui and take over the Matoran Universe. Teridax disguised himself as Turaga Dume and hired three Dark Hunters, Nidhiki and Krekka inside the city and "Eliminator" outside it, to get rid of the Toa Teams protecting Metru Nui at the time. He succeded, but not before new Toa were created to guard the city: the Toa Metru. For their first mission, these new Toa destroyed the Morbuzahk plant that was threatening the city with the help of the Great Kanoka Disks. The Toa Metru hoped that they proved heroes to Turaga Dume and that he would name them the new protectors of Metru Nui, but Dume (Teridax in disguise), declared them as traitors. He ordered the Vahki and Dark Hunters to eliminate them while he started gathering all the Matoran and putting them into Matoran Pods. The Toa Metru then faced him and imprisoned him in a protodermic cage. However, the Visorak hordes soon took over Metru Nui but were defeated by the transformed Toa Metru with the help of Keetongu and the Rahaga. In the process, the Toa accidentally released Teridax from his prison, but managed to save the Matoran and bring them all to Mata Nui. Metru Nui was then watched over by the real Dume, Keetongu and the Rahaga for 1000 years. During that time only one gate to the waters around Metru Nui was open.

Metru Nui would wait until Teridax was defeated again by the Toa Mata, and later, Takanuva. After the battle over the Mask of Light, the gate to Metru Nui via Mangaia was once again opened. The Matoran made their way to their "old" home, and settled it once again. The battle against Teridax was taken to other fronts, and Metru Nui was finally safe. The Matoran first settled in Po-Metru because it was the least damaged. They started to rebuild Metru Nui but weren't finished before the Staff of Artakha was used on Daxia and repaired the whole island. During this time, the Matoran from Karzahni were moved onto the island by the Toa Nuva.

During the Destiny War, the Rahaga returned to Metru Nui as Toa Hagah, along with the mutated Piraka Zaktan, in order to try and stop Teridax before he took over the mind of Mata Nui and the Toa Nuva would awaken the Great Spirit with Teridax in his body. Teridax made the Toa Hagah leave, thinking they won the battle, but have not returned to the surface yet.

Also, an Order of Mata Nui agent sent Toa Mahri Jaller, Hahli and Nuparu to Artidax with the Heart of the Visorak, in order to destroy that species once and for all. Their boat was stolen by Takadox and at the time of the last update to the Dwellers in Darkness story serial, they were swimming back. Presumably they made it back by the time Mata Nui awakened.

When the Toa Nuva awakened Mata Nui, they returned to Metru Nui with the Av-Matoran of Karda Nui to celebrate their destiny being achieved at long last. However, the celebration was interrupted by Teridax's announcement that his plan 80,000 years in the making had finally been accomplished. Rahkshi swarmed into Metru Nui to ensure the Matoran kept working so that the new Great Spirit, Teridax, would not succumb to illness like Mata Nui did twice.

At the time of the latest story update, the Matoran, Toa, and Turaga of Metru Nui gathered together in the Archives for safety from the Rahkshi. They met up with Krahka who volunteered to help them get through tunnels that go to the shore, steal a boat, and meet up with some of the other less than 50 Toa left in the universe. It is unknown how well this plan worked, but since Teridax ensured that he got rid of all possible threats to him in his universe (the other Makuta, Mata Nui's spirit, and the Ignika), it is doubtful anything became of it.



Position
Metru Nui was located in Mata Nui's head, and served as his brain. As such, it was the northernmost island in the universe. It was nearby the following islands:
 * Karzahni to the south, connected to Metru Nui via series of mountain ranges and a short isthmus, jutting into the Karzahni dome.
 * Xia to the south-east, it can be reached by sailing out of Metru Nui through the main southern sea gate, and then turning sharply east, following the Great Barrier.
 * Zakaz was directly south of Metru Nui, but could presumably not be reached by simply sailing south because the island of Karzahni would be in the way.
 * The Northern Continent was also south of Metru Nui, shortly west of Zakaz.
 * Two unnamed islands in Mata Nui's left shoulder, far southeast of Metru Nui, one of which Toa Mangai Naho may have swam to for help during the Toa-Dark Hunter War.

Environment
The city of Metru Nui was, like the rest of the Matoran universe, inside of the Great Spirit. The Matoran living there were unaware of this, however; mists obscured the cavern walls (called "the Great Barrier") and gave the appearance of a normal sky. There were also two holes in the ceiling, which looked like two suns to Matoran living on Metru Nui, but were in actuality the eyes of Mata Nui. These two holes had a barrier over them so water or other things would not be able to fall through. One hole is believed to be in Naho Bay on the island called Mata Nui, while the other under the ice of Mount Ihu on the same island. The city also stood in the center of a vast "Silver Sea" of Liquid Protodermis.

District System
The population of Metru Nui was dispersed throughout six "districts", each specializing in a specific element and occupation, and the central point where many things took place.

Coliseum
The Coliseum was at the center of the city of Metru Nui, where the borders of the six districts met. It was where sporting events such as Akilini took place, as well as being the main power station for the city. It also served as the Turaga's home. When the Visorak invaded the city, they made the Coliseum their main nesting grounds.

Ta-Metru
Main article: Ta-Metru Ta-Metru was the place where Protodermis was molded and manufactured after it was rid of its impurities in Ga-Metru. Because of all the smoke and heat from the foundries and forges, Matoran from other districts did not like to stay here long.

Ga-Metru
Main article: Ga-Metru Ga-Metru was the center of learning in the city, where the schools and research labs were located. This was also the district where Liquid Protodermis was taken from the Silver Sea and purified so that it could be used elsewhere, there were canals for Liquid Protodermis everywhere. Ga-Metru was very peaceful. The Great Temple was also located in Ga-Metru.

Le-Metru
Main article: Le-Metru Le-Metru was the transport hub of the city. Le-Matoran were in charge of the entire city's transport network, particularly the system of chutes that moved Matoran and things between Metru. The flurry of activity and the number of wires strung about gave the district the feeling of an urban jungle and of barely controlled chaos. Le-Metru's Moto Hub was the largest chute station in Metru Nui, as well as the administration building for chutes, where the main controls were located. There was also a Test Track, where new vehicle designs were made and tested by volunteer Matoran.

Onu-Metru
Main article: Onu-Metru Onu-Metru was home to the Archives, an underground museum complex where Onu-Matoran archivists worked hard to preserve artifacts of Metru Nui's history. The archives have actually expanded again and again, to the point where they stretched underneath the whole city. Besides just artifacts, Rahi were also kept in the Archives. Deep down, many things are stored, including large rahi. Even Toa Whenua was scared to find out what thrives down there.

Po-Metru
Main article: Po-Metru Po-Metru was the most natural of all the city districts, as it was made up mainly of rocky mountains and canyons. Po-Matoran liked to work outside, assembling goods and carving statues. Rahi attacks and stampedes were somewhat common in this district. Po-Metru's claim to fame were the Sculpture Fields, a large expanse where Po-Matoran worked to carve giant statues much too large for any building. There is a Brotherhood of Makuta base located here.

Ko-Metru
Main article: Ko-Metru Ko-Metru was known best for its Knowledge Towers, which are crystalline structures that could reach so high that their rooftops were often covered with ice. Ko-Matoran were scholars and seers who studied and analyzed, trying to predict the future. The district was kept incredibly cold, in order to better preserve written documents. Ko-Metru was the quietest district in the city, as Ko-Matoran hated to have their work interrupted. The mythical Rahi Keetongu also made his home in a Ko-Metru cave.

Inhabitants
The primary inhabitants of Metru Nui were Matoran. For roughly 100,000 years there were only six types of Matoran in Metru Nui: This was because these six types were considered by the Great Beings as the most important types of Matoran. Recently, the Matoran of Karzahni have come to Metru Nui, and presumably there are more Matoran of other elements among them. The Av-Matoran from Karda Nui were also brought to Metru Nui after Mata Nui's awakening, due to the Energy Storm raging in their former home.
 * Ta-Matoran
 * Ga-Matoran
 * Le-Matoran
 * Po-Matoran
 * Onu-Matoran
 * Ko-Matoran

Transportation
The beings of Metru Nui moved throughout the city using "chutes", air-filled magnetically-powered tubes in a network managed by Le-Metru. However, the chutes were not the only way to travel around Metru Nui. There were also Airships, Moto-Sleds and many other vehicles Matoran used for transport. Cargo was transported with Cargo Haulers and Vahki Transports were used by Vahki to transport Rahi or other materials.

Daily Life
Most Matoran stayed in their districts, working in a specific job type. The Ta-Matoran worked using the molten protodermis to create Kanohi masks, Kanoka disks, and other tools. The Le-Matoran were in charge of the chute system, the Ga-Matoran specialized in education, and the Po-Matoran were good in architecture, sculpting, and craftsmanship. Onu-Metru ran mining and the Great Archives, a massive zoological, scientific, and historical project. Ko-Matoran would meditate in their knowledge towers, providing needed insight and philosophy. Metru Nui has consistently run this way, interrupted only two times: by the Metru Nui Civil War, for 600 years, and by the Great Cataclysm, for 1000 years. Since Metru Nui served as the Great Spirit Mata Nui's brain, the Matoran working acted like brain cells, and had to stay working for Mata Nui to stay healthy. When the Civil War kept Matoran from working, Mata Nui fell ill and Jovan and his team had to use the Ignika to revive him. When Teridax unleashed his virus on Mata Nui, he drove the Matoran out of the city, and they would need to return to work before Mata Nui could be awakened.

Crime
In a city as large as Metru Nui, unsavory Matoran were common in place, and so were their deeds. Everything had value, stolen or not. This was exploited. Metru Nui had a vast black market, with many customers and products, ranging from counterfeit widgets to a wild Rahi.

These were the main crimes:
 * Forgery
 * Disk Dueling
 * Smuggling and Theft
 * Destroying another Matoran's Kanohi

Vahki
The Matoran were protected and policed (sometimes violently) by mechanical inventions like the Vahki. This force held powers of coercion and powerful persuasion to help them deal with criminals. The Vahki that were not destroyed in the Great Cataclysm were slaughtered by the Visorak hordes. It has been confirmed that there are no remaining Vahki.

Rahkshi
After Teridax's takeover of the universe, law enforcers returned to Metru Nui in the form of Rahkshi. The Matoran hid underground from them at first, but presumably Teridax forced them to get to work, and they fell into a new life under the supervision of the Rahkshi.

Toa
Metru Nui has been protected by Toa Teams throughout the ages, whether slaying legendary Rahi or serving and defeating the Brotherhood of Makuta. Toa passed power down to ordinary Matoran, continuing the cycle of having venerable superheroes to defend the city. Some of the teams protecting Metru Nui were:
 * Toa Mangai- formerly, all of them are deceased
 * Toa Metru- now Turaga of their own Metru
 * Toa Nuva - currently guarding Metru Nui
 * Takanuva - currently guarding Metru Nui
 * Toa Mahri - currently guarding Metru Nui
 * Teridax's Toa Hagah team- returning to Metru Nui after seeking Teridax beneath the Coliseum

Disks
Kanoka disks were used as common weaponry and tools for the Matoran. These disks had adaptive powers according to their codes and elements. Unfortunately, this developed into the popular but illegal sport of Disk Dueling.

Trivia

 * Fans have translated "Metru Nui" into "Great City". This means that Ta-Metru means fire city, Ga-Metru water city, and so forth.
 * Metru Nui has appeared in most Bionicle sources, since Mata Nui and its inhabitants are actually part of Metru Nui.
 * Interestingly, Metru Nui is the same shape as the Island Mata Nui. This was recently revealed to be because said island is actually a camouflage system that naturally forms when the Great Spirit lands on a planet to observe it, and it is designed to manifest itself in the same shape of Metru Nui, the Great Spirit's brain.