The Primus Hexaconta is a sixty-sided polygon structure in the southern tracts of Honmin. It is otherworldly appearing, looking like a mix of petrified matter that was once living and clockwork parts locked in place. The strange appearance is because the Primus Hexaconta is the heart of the Prime Architect. When this primordial was killed by the Nine-Tongued Worm, his heart shot out of an aperture in his back and then flew over the horizon. It came to rest on the Kirrothe plateau and began to uncompress. It increased in size by a thousand fold, taking up an area a half a mile in each direction.
On 3 Dreamer 8612 DE, the day of his end, the Prime Architect transferred all his life energy and hundreds of Sparks of Creation into his heart. Much of the life energy went into creating his only son Primus. Some of the Sparks of Creation were used by Primus to build a modron army to keep the Primus Hexaconta from the primordials and their minions engaged in the Dawn War.
Primus, son of the Prime Architect, is largely responsible for keeping the primordials out of Hezmort. His modron legions, and their efficiency, order, and military discipline made them a bane to the minions of Chaos.
After the Dawn War, Danzar-Khâl put Mechanus under the oversight of Primus and his modrons. The Primus Hexaconta was left under the guardianship of constructs and magical creatures. The place's traps, guardians, and puzzle locks were enough to keep most away. Those that made it in past the initial defenses often found themselves lost in shifting chambers and rotating levels which is like a multi-level maze. In the Demon Spawn War, Jurusalax had great interest in the place. The loss of hundreds of demons and slaves in the place caused him to give up on exploring it. It is thought that he "befriended" the Gimrune because they seemed like the type that could unlock the place's secrets.
The Gimrune under Jurusalax and his demons failed to make any progress in the place. After the Demon Spawn War, the place came to be a forbidden land, too dangerous to go near for the wild beasts in the forests around it and deadly to any foolish enough to enter it.
During the start of the Feeding of Kezgihr, hundreds of Gimrune from frontier towns fled the blood-starved vampires coming across Barba'gom. They made their way towards the Primus Hexaconta. The Gimrune that went to this ancient forbidden edifice decided that it was safer facing death by such creatures, than becoming a blood slave to the vampires or becoming one of them. In the Primus Hexaconta, they hid from the prowling vampires of the countryside. At night they barricaded the place, but rarely had to deal with a vampire bold enough to enter. During the day they tended the fields around the ancient edifice, then by dusk return to its safety. In the Primus Hexaconta, they found a number of secret chambers with blueprints and instructions for making constructs, mechanical contraptions, and replacing organic parts with mechanical grafts. After finding these, they now new why the place had such massive storage chambers holdings limbs, molds, preserved eyes and other organs, mechanical attachments, and so on. The blueprints that left the most lasting mark on the Grimrune of the the Primus Hexaconta are those on grafts. These grafts were not like maug grafts and others made for the Machined, instead they are made with a bit of a Spark of Creation. This keeps the host mortal and not turning into a half-golem when they add three or more mechanical grafts. The Gimrune were also soon to learn that being grafted made them invisible to the heat seeking sight of the vampires. It also had the plus of them not being sought out for feeding since a grafted Gimrune was much more of a danger than some peasant.
After four generations in the Primus Hexaconta, the people of it became known to Gimrune outsiders as the Shi'gah. These half-clockwork Gimrune have lived in this place since the time of the vampires and spread outward east and west. Today, the Primus Hexaconta is more a medical lab and experimentation area than living quarters. In the medical areas, Shi'gah doctors apply grafts to those with the coin. In other areas, they manufacture golems and clockworks to bolster the armies of Dema'tira.