The Hall of Crafting is located inside Blackrock Depths, deep within Shadowforge City. It can be accessed either through the Domicile and past the Black Vault, or by going through a Shadowforge Key-locked gate and past the Dark Iron Highway.
This rocky region is populated with groups of one elite golem and 3 non-elite Dark Iron dwarves. The area is a square staircase leading upward from the Black Anvil to the upper levels of the city. Fineous Darkvire patrols from one end of this area to the other. He is the NPC that drops Ironfel, which is required for a quest to obtain the Shadowforge Key.
As the name implies, this is where the Dark Irons carve their golem protectors from soil and mud, later to be forged with iron and steel in the Mold Foundry.