In the original structure both outer and inner walls were built of hewn blocks of tufa and limestone; but we find portions of the outer wall, and all the towers, of lava rubble, the surface of which was covered with stucco. The towers were already standing, as shown by inscriptions, at the time of the Social War. We are therefore safe in believing that in the period of peace following the Second Punic War the walls were not kept in repair, some parts of the outer wall being utilized as a quarry for building stone; that with the advent of the Social War they were hastily repaired on the north, east, and south sides, and strengthened by towers, but that no attempt was made to renew the fortifications on the steep southwest side, between the Herculaneum Gate and the Forum Triangulare, where the line of the old wall was covered with buildings. [Illustration: Fig. 109.--View of the city wall, inside, where the embankment has been removed. The door in the tower at the left marks the height of the embankment.] When the towers were added--probably not long before 90 B.C.--they were not distributed evenly along the wall, but were placed where they seemed to be most needed. The western portion of the ridge between the Herculaneum and Capua Gates was particularly favorable for the approach of an enemy; hence three towers were built near together here, numbered 10, 11, and 12 on Plan I. Another part of the wall especially exposed was on the southeast side, where the height covered by the city slopes gradually down to the plain; and we find five towers within a comparatively short distance, two east of the Amphitheatre, the other three further south. On the north side, between the Capua and Sarno gates, the slope is steeper and two towers were thought to be sufficient. That there were once two additional towers, besides the ten that have been enumerated, is evident from several Oscan inscriptions, painted in red letters on the street walls of houses. One of them, near the southwest corner of the house of the Faun, reads thus: 'This way leads between Towers 10 and 11, where Titus Fisanius is in command.' The street referred to runs between the tenth and twelfth Insulae of Region VI, direct to the city wall. Two others refer to a 'Tower 12' near the Herculaneum Gate, this part of the fortifications being in charge of Maras Adirius. In a fourth inscription we read: 'This way leads between the houses of Maras Castricius and of Maras Spurnius, where Vibius Seximbrius is in command.' In 1897, a fifth inscription became visible on the north side of Insula VIII. v-vi, where it had been concealed by a coat of plaster: 'This way leads to the city building (and) to Minerva.' The street referred to is seemingly the blind alley which formerly ran through the insula (Plan I). If this is correct, the sanctuary of Minerva is the Doric temple in the Forum Triangulare; but the 'city building' cannot be identified.