437 metres and of the short sides, the northeast measures 224 metres, while the southwest measures 239 metres. The total area, therefore, is around 95,000 square metres. Northeast side At the end of the northeastern side of the circuit wall, probable traces of a circular turret were found within the building of the Society of the Sacred Heart near San Paolo until the building's complete destruction by Allied aerial bombardment during the Second World War. Today, this is the site of an episcopal seminary and a centre for vocational training. The circular room inside the convent, described before the war, had a diameter of 3.63 metres and was covered by a low dome of very poor workmanship, probably a modern repair. Going along the Roman wall, it is better preserved stretch for about fifty metres, because it serves as the boundary wall between the property of the episcopal seminary and the Missionaries of the Precious Blood, which govern the church of San Paulo. This stretch was built with very great care, because it had to function as the external retaining wall as well, to a depth of four metres. For this reason it is also very monumental and robust. No trace remains of the porta decumana which must have been around the middle of this stretch and was probably accessed by a staircase of a ramp. Past the Via San Francesco d'Assisi, on which the Medieval gate of the Cappuchins opened until the second half of the Nineteenth century, the wall follows the Via Tacito, on the property of the Daughters of Immaculate Mary. At the corner of their property, the rounded corner of the ancient wall is still visible, but the circular turret is not, though the need for the wall to bear its weight is reflected in the stronger structure of the wall. Southeast side This is the best preserved side, including the remains of a rectangular guard tower and of the porta principalis sinistra as well as a long stretch of wall, preserved for 142 metres on the Via Castro Partico. Turning onto the Via Castro Partico, still on the property of the Daughters of Immaculate Mary, sixty metres from the rounded corner, the wall contains a rectangular guard tower, currently put to use as a farmhouse. The internal space measures 5.90 x 3.85 metres and the walls are 0.90 metres thick (except the exterior wall which