The Great Furnace was a massive foundry in Ta-Metru1 used for the creation of Vahki parts and other essential items. It was once the second highest structure in Metru Nui, after the Coliseum. The heat from the furnace was so intense that Matoran could withstand it only for a few minutes at a tie before needing to retreat to the slightly cooler outer ring in the structure. The Great Furnace operated day and night, producing the largest amount of material of any material of any forge or factory in Ta-Metru. After it was destroyed when the Toa Metru defeated the Morbuzakh, it was never rebuilt.2
Notes
Flawed Kanohi masks from the Protodermis Reclamation Center were melted down in the Great Furnace.3
Flawed protodermis creations were melted down in the Great Furnace for later recasting.4
The Great Furnace in Ta-Metru was the biggest source of heat in Metru Nui.5
The Great Furnace was the most significant source of heat in Ta-Metru apart from the fire pits.6
The Great Furnace was not as big or imposing as the Coliseum, not did it have the feeling of power and mystery that the Great Temple had. Still, every Ta-Matoran looked at it with awe and wonder. It was a symbol of what made Ta-Metru great: the power that turned solid protodermis to molten liquid, and the skill to shape that raw material into the tools Matoran used every day. The exterior of the Great Furnace was reddish-black. The entrance to the Great Furnace was a massive locked door. Just inside the door was a small, bare chamber. Its purpose was to give Matoran a chance to prepare before they proceeded into the inferno inside, or to give them a chance to rest after they had spent some time laboring in the furnace. Beyond this chamber was the outer ring, a buffer to keep the intense heat from reaching the outer walls of the building. The door leading to the outer ring opened to a long narrow chamber lit by dim lightstones with a stone floor. A door led from here to the inner chamber.6
The massive inner chamber of the Great Furnace was transformed into a sanctuary for the king root of the Morbuzakh.6
The Great Furnace was completely reduced to rubble and flames by the battle between the Toa Metru and the king root of the Morbuzakh.6
The Great Furnace was a massive structure that dominated the central part of Ta-Metru.7, 8
The Great Furnace stood out above all the other factories and furnaces in Ta-Metru. It towered well over a thousand feet in the air, second in height only to the Coliseum. Its heat was so intense that even Ta-Matoran could not work there for more than a few minutes at a time.9
A short time before story year 2004, workers in the Great Furnace were being attacked by massive vines that appeared from nowhere and disappeared again. Fearing for their safety, the workers fled. The Great Furnace eventually became the hiding place for the monstrous king root of the Morbuzakh. During the battle between the Toa Metru and the Morbuzakh, the Great Furnace was destroyed, and had yet to be rebuilt.9
As of mid-story year 2004, the Great Furnace was "closed for renovations."10