15thc perception on swallowtail merlons?

[Mauro]

@MarcoP @Jorge_Stolfi
A new source I've come across suggests that Marin Sanudo’s sketch should be understood as referring to the Cidneo (Castle) Hill and not the opposite end of the citadel, as I had assumed. This means the label in the middle should not be read as "Garza". 

Not necessarily. Below I labelled the map you posted You are not allowed to view links. Register or Login to view. along with a view of nowadays Brescia from google maps:

   

The view of the Cidneo castle could be from beyond the Garza river looking towards East (in the undistorted Google maps, the medieval map is distorted and the look seems from south-west towards north-east).

In the medieval map there  is also a set of walls more or less between the Garza and the castle, which I guess might be the Citadel, but I would not count much on those being actually there, due to the distortion. I think the Cittadella Nuova walls began near Piazza Tito Speri, at the south-west tip of the hill.

Nowadays the view of the Castle and of the Cidneo Hill from the East side is unimpressive because the hill is encroached by the houses of Contrada Santa Chiara. I don't know if the view was better or if there were orchards there in ancient times (while I'm sure there were on the south side of the hill).

PS.: if the writing on the Sanudo maps is actually "fosse zoè lagarza" I guess he mistook the name, he believed it to be "Lagarza" (the Garza). In Eastern Lombard the names of rivers are always preceded by the determinative article 'la' ('la' because they are feminine), and I guess it is so since ancient times. So a mistake easy to make.