15thc perception on swallowtail merlons?

[Pierre Dumont Himself]

The Garza used to flow along the Via San Faustino and next to the main squares, which were once centers of industrial and commerical activity by the river. The 1184-6 wall was built along the Via delle Battaglie to protect this area. The Garza later functioned as a moat of the Cittadella Nuova. You can see it clearly on this map from 1470, originially in the Ms. H.V.5, or Book of Privileges, now preserved separately. 

The internal walls were demolished by the Venetians in the early 16th century. The Garza was diverted at the same time, and the squares were built soon afterward.