The Empire did know what a Tower was.They simply dind’t know where the Tower of Uru was.They were waiting for Craymen to move.
Well somehow the Empire found the location of the Tower of Uru. The 7th Emperor knew Craymen was planning to go after “those ruins” when Craymen destroyed the capital to slow the Empire down.
I’m curious as to know the Empire found its location. I bet there’s some interesting information regarding the Ancient Age locked away within the Imperial Accademy.
As Azel was stored at Excavation Site #4 since the Ancient Age ended, as the site had existed for over twenty years, as both Craymen and the Empire seemed to know of Azel’s capabilities before she was actually recovered and as they both knew she could be used to activate the Tower of Uru, I thought it was likely they’d just found some ancient logs at the site. Along the lines of “We’ve got the stolen Drone stored on the fifth floor. This is the location of the Tower we’re going to use her to take control of.” 