Gunsmith's Forge is a Dwarfs military recruitment building in Total War: Warhammer. The secret of black powder, formulated here, is one shared only between the Empire and Dwarfs.
Background
The powder hall is a part of the Hold not visited often by those who do not work there, for should a naked flame be brought in then the chances of survival are small. Along the blackened walls are many barrels that contain the ingredients for black powder, which, when formulated, is used to power the most deadly weapons in the Dwarf arsenal.