Well,My way of thinking this could be better is..
-Don't double layer using 5x bricks,Use bricks (Precisly nothing taller or wider then 1x.)
-Color to be more fitting,Use ramps.
-Put valves in a more secrete area,Color them differently.
-Use fire emitters inside,not on the wall.
-Torches should not be metal/stone,They should be wood.
-Fountain needs too be on either a 8x8F plate or a 16x16 Baseplate
-Don't use unoldo,its ugly.
-Alarms should be activated through toggleEventenabled,not 2 switches,Same with valves.
-"On" and "Off" should go,Replace it with something more fitting towards the area.
-Use bubbles,foam and less Water A for the fountain.
-Make the fountain more white other then gray,It just doesn't look good.
Well,Thats just my ideas on how your castle could look better.