Because the defense needs had to prevail over those of road conditions, the level road that it is currently seen didn't exist at that time and it was instead an up and down path on certain points of which flowed, passing under the houses. 
Short descended from the parallel immediately above, that the wide road and currently Via Roma, apparently in order to facilitate the movement of defense of the castle towards the walls and the portam castri. Rughe are characterized by the vaulted roofs stone round arch or plank, the powerful pointed arches or round arches that sustain it, the loopholes from which they get light and in the Middle Ages were also a place of defense from attack.