Unfortunately I can’t find the excellent video about why rain must not be allowed to cascade down walls, but it proved that it was very dangerous to building integrity, and it gave extensive explanation of why castles have pipes to drain rainwater at a distance from the wall. If you want to search for it, I think the old title mentioned “gargoyles” but youtube may have removed it.

Near where I live there is an old factory with brick supporting square ‘tower’ and a larger iron tank for water(?) on top. Of course the tank holds more than the base dimensions, but it is more striking. I think in the same way castles had a larger top sections with the jettying, because it became more dynamic to the eye. Ones approaching enemies would see the structure’s towers more clearly as it was bigger and thus made aware of its majesty and perhaps its strength. More a case of ‘look how powerful we are to create this extra.’