I remember taking a tour of a castle in either Belgium or western Germany while I was assigned to US Army Europe. One of the items on the tour was the privy/toilet on one of the upper floors. It was a narrow room with several holes in the wooden planks, like an old fashioned outhouse. One’s droppings fell into the space between the inner and outer walls of the castle.
One I liked was Chillon Castle on Lake Geneva, same thing holes in planks but it dropped 100 feet to the lake. As a side note this is where Mary Shelly wrote Frankenstein one summer, Lord Byron was there at the same time