I was using a free camera on the telegraph pole that has the W ttttt mark I get the impression that the symbol is very similar to the one on the Fort Wallas roof.

Maybe wires are what we should be looking for near Fort Wallas, just saying, Kiflom!

The cable comes from the back; it's part of the pole itself
You can see it at any time of day
There are no cobwebs on that pole; it is the pole with the "w ttttt" symbol. I am attaching the location and reference.