Beginning with the Palatine and working counter-clockwise, Säflund examined every inch of the surviving circuit ascribed to Servius (see Fig. 2.3), and for stretches which had been torn down during Rome’s great expansion (after she became the capital of a united Italy in the 1870’s) he had access to unpublished notes and sketches by Boni and another great nineteenth-century Italian archaeologist, Rodolfo Lanciani. Everywhere he paid careful attention to materials, techniques, dimensions, mason’s marks, the relation of the wall to terrain, neighboring tombs, and ancient artifacts found in its context. It was chiefly from the building material that Säflund drew his conclusions. The stone was in the main Grotta Oscura tufa, which he knew from Tenney Frank’s studies to have been in use in the year (378 B.C.) in which Livy says the censors contracted to have a wall built of squared stone. Furthermore, some of the Esquiline tombs already mentioned, containing mid-fourth century artifacts, were outside the line of the Grotta Oscura wall, while some of the tombs containing archaic artifacts were inside. The Romans rarely buried their dead within a city wall: the inference is that at the date of the earlier tombs, Rome had no proper ring-wall, while by the date of the later (fourth-century) tombs a circuit wall had been built. The Great Drain through the Forum is also of Grotta Oscura, and is therefore probably to be dated in 378, like the wall, though some feeder lines are in _cappellaccio_, which, as we have seen, was the earliest volcanic stone the Romans used, and we know--because we know the Forum swamp was drained by 575 B.C.--that there must have been some sort of drainage system--possibly open ditches--earlier than 378. But Säflund found Fidenae tufa also. This he knew, again from Frank’s study, to have been in use from about 338 B.C. down into the second century. It had been used to patch the wall in places. What more appropriate time for such repairs than when Hannibal was threatening the city, in 217 B.C.? Thereafter, Roman and Latin colonies, advanced bases, served her in the office of a wall, and her own fortifications were allowed to fall into disrepair. But there are places in Rome’s wall where Monteverde stone has been used for arches, rising from footings set in concrete; in other places the wall has a concrete core faced with Anio tufa. Säflund knew that concrete was little in use in Roman building before 150 B.C., and that it had become a favorite material by Sulla’s time (see p. 129). Sulla had marched on Rome in 88 B.C. and taken it; he must have reinforced the wall to keep his enemy Marius from duplicating his own feat. And Sulla included the bridgehead on the far side of the Tiber in his circuit, reinforced the Aventine Hill, and added _ballistae_ (great catapults for shooting stones) in arched casemates flanking the main gates.