| Category | Marvels |
| Continent | Brucrumus |
| Region | Great Expanse |
| Owner | none |
| Built | unknown |
| Map | Nemertes |
In 1482, a colossal clockwork gear fell through a inter-system rift, landing in the heart of the Great Expanse. A device of Modron construction, it is 1900' in diameter and 300' thick at its center, tapering to 100' at its edges. Built on the world of Regulus, a Modron team was sent to disable and begin the dismantling. For these teams and others, tampering always led to them going "rogue"; allowing them to think independently, outside of the rigid hierarchy of their kind.
The Gear Monument came with several stowaways. One of these was a rogue modron named Tetretz; an authority on machined creations like clockworks, the Maug, the Warforged, the Modron, and various automations.
Around 1485, the Gear Monument began producing living constructs, clockwork, Maug and the Warforged. Using the Gear Monument, they created more of their kind, often just sending them off to roam the landscape. Some collected into groups and then formed holdings of their own; the largest being Helmogorn.
Once part of Primus's home world, the Gear Monument serves as his top holy site on Bal-Kriav.