The Cliffs of Moher

[Doireannjane]

I just looked through all of them and none of them look remotely close to the drawing and very few are near water.

The point is that the merlons are not a random design. They do not happen by chance. They never happen in Ireland.

So that's why I said these were peripheral items. The castle is subjective and could be just imaginative. I personally see more similarities with Irish castle there and the swallowtail adjacent shape could be reflective of the artists memory or background. Time spent in both Ireland and in Italy was not unheard of for friars or nuns. 

I think it's also important to just note that aside from the swallowtail, the castle itself does not look like any of the Italian castles.