This investigation aimed to uncover the possible existence of a link, across a section of the pomerium, between via di Narciso and vicolo di Modesto. This route appears on Bibent’s plan of 1862 and on other plans derived from it. Unfortunately no evidence of any road was found in the section investigated in depth, apart from the sparse remains of a badly preserved beaten earth surface. However, a wall (USM 1) was completely uncovered. Built in blocks of trachytic lava, its function was to contain the earth forming the embankment where it was not sustained by the steps giving access to the walls. When the area investigated lost its original function, it was used as a dump, from the post-Sullan period until the days immediately before the eruption of 79 A.D. Lastly, in the modern period (1700-1800), given its elevated and marginal position, the area was used as a route for dumping the earth removed from ancient excavations. In fact, a two-lane road with the ruts worn into it by the carts used to transport this material was revealed. Below was a beaten earth road surface with the hoof prints of pack animals still visible.