This being the first stratigraphic unit preserved below the level to which the Sopraintendenza excavated, its reliability is not good. Below this layer was found a course of ashlar blocks, which must represent the eastern wall of the complex; thus this layer is post-abandonment of the first phase of the complex. Based on its position and elevation with respect to the opus mixtum wall 5311, this layer seems to represent the fill of a foundation trench for that wall. However, no construction cut is visible, presumably because the limit of the 'cut was the curb to the east.