The vast and ruined Black Towers remain, far from any Walled Cities. They emit the aura of great tombs, and it is rumored that endless dead remain in them, but as powerful creatures now reside there it is rare for anyone to venture in.
Occasionally a Relic band of heroes attempts it, and if they emerge they do so carrying "memories". Chunks of data that contain huge quantities of information from pre-(H)istory. These can either be relatively worthless (although interesting) as many contain extremely mundane and non informative loops.
Rarely, however, it allows the viewer to walk through great libraries, or secure facilities, or see into the inner workings of the highest level factories.
Once removed from the tower these data chunks slowly degrade, until they are nothing more than haze and fleeting emotions.
Still, the towers feel endless, and likely we will never fully mine the heights.
Perhaps it would be best if we could move on, but it is impossible to resist the knowledge of the past.
-Writings of the Historian Costanza Godhand