if you need to have wires on the facade of an historical building doesn't it makes sense to expend (probably no more than 20 euros) on hooks and nails so that the cables are at least straight and not a random mess.
As for me, they should be somewhere inside the building, for example in the staircase - but maybe it would be problematic to pull them somehow onto the roof. So they are on the facade. And again it is not easy to attatch this cable, since it's quite high. They would need a special crew which can work on heights, or at least they would have to rent a scaffolding.