Accessible through the basement of the Monastery of Saint Thomas Aquinas, the Forge was preceded by a series of tunnels, at the end of which was a large room with the mold for the Shattered Staff of Eden. Despite its age, the Forge was still able to function enough to completely repair the Staff.
The vault was discovered by Inquisitor General Tomás de Torquemada, a Master Templar of the Spanish Rite of the Templar Order, some time prior to 1498. Once Torquemada had acquired all three pieces of the Shattered Staff of Eden, he used the Forge to repair it and spent weeks at the monastery above and vault below studying it.
In 1498, the Spanish Brotherhood of Assassins tracked down the Templar and fought both him and the apparitions conjured by the Staff, eventually emerging victorious and reclaiming the Staff. To avoid it falling into Templar hands again, it was destroyed using the collapsing Isu architecture in the Forge. The ancient vault disappeared, buried under the Monastery of Saint Thomas, and the remains of the Staff of Eden along with it.