See my post above, there are very skillfully concealed "gutters" below the blue roofs of the turrets disguised as stonework, the white PVC is almost certainly used to drain the gutters as they sure will fill up with water when it rains (probably already have).
The actually grounding wire wouldn't be nearly as visible as PVC drainage pipe, since it is much smaller diameter, and also is not white. Its in there for sure. The tops of the turrets are conveniently made of metal, and hence are bonded to the grounding wire.
Interestingly, if all that was going in the turrets was drainage pipe, and already installed grounding wire, no need to have a square section of dry wall cut out/or not dry walled over yet. IMHO, they are going to put in something like Speakers, or security cameras, here. Probably speakers hidden by foam spray painted to look like stone work, or hidden behind a "window" or stonework or something.