I'm not certain but isn't the current tower newly built and not found? If newly built then how does zavala or anybody else not know of the black armory. If it was existing, would you not scope out the whole place? hidden walls? Well any ghost can easily scan and detect it.
YES!!! This bothers me the most! In triler Zavala is helping build wall. So Ada with Black armory is hiding since golden age within wall that does not even exist since golden age...