is inexplicably only 0.59 metres thick). The entrance is still that used in antiquity, facing the inside of the castra and is 1.78 metres wide. The wall then continues on the property of the modern Liceo classico statale Ugo Foscolo and around two hundred metres further on, the remains of the porta principalis sinistra are found - the only one of the two portae principales which can still be seen. The gate, considered one of the most beautiful remnants of the castra by the archaeologist Giuseppe Lugli, consisted of a single archway where the ashlar blocks meter with the horizontal ones of the wall. It is 3.85 metres wide and no traces of guard towers have been found on either side. Along from the gate, next to the old civic hospital building (now the municipal police station) traces of the wall can no longer be made out. Nor do any traces remain of the rounded corner fortified with a circular tower, which must have been located at the end of the modern Via San Francesco d'Assisi. Southwest side Some remains of the wall on this side were found in 1913, during the construction of the modern piazza Giosuè Carducci (), and more have been incorporated into the foundations of modern houses. The most substantial remains on this side, however, are those of the porta praetoria, right in front of the Palazzo Savelli. Located at the midpoint of the wall, the gate was incorporated into a later building, preventing the "liberation" of Roman monument, until the devastating Anglo-American aerial bombardment of 1 February 1944. The central archway measure around 3 x 5 metres with a height of 14 metres while the two side archways were a little over 1 x 5 metres. The two side chambers each measure 5.40 x 5 metres. Further to the north, the wall is visible for stretches on local land, facing Via San Pancrazio. On the same street, the well-conserved remains of a circular guard tower can be accessed, 3.40 metres below the modern ground level of the Via Alcide de Gasperi. The construction poses a problem: the vault of the single room is only 1.60 metres above the level of the intervallum and even allowing for the existence of a second story (per Giuseppe Lugli), the tower would not have reached a plausible height to be a guard tower. The conclusion is that this was