Palazzo Antonelli

Ancient sources credit the sixth king of Rome, Servius Tullius, for the construction of the first circuit of fortification walls of the city in the mid 6th century BC. Alternatively, a few authors attribute the project to his predecessor, the king Tarquinius Priscus.

Much has been debated among modern scholars on the extent and location of these walls, and some have even questioned their existence. Recent discoveries, however, have shown that fortification walls were built in the cities of Latium already by the 6th century. At Rome, in particular, the use of ashlar masonry in cappellaccio tufa, a friable granular stone associated with archaic buildings, seem to confirm the historical accounts.

These earliest defensive structures proved to be inadequate to protect the city from the Gallic invasion of 390 BC and were therefore replaced by a new circuit of walls, made of tougher tufa from the quarries of Grotta Rossa that became available after the conquest of Veii in 396 BC. The second structure followed almost exactly the pre-existing walls in cappellaccio; its exact date of construction is mentioned in Livy (VI, 32,1) who reports that in 378 BC the censors Spurius Servilius Priscus e Quintus Cloelius Siculus were commissioned the construction of the new walls in ashlar masonry (saxo quadrato) to better protect the city. Restorations followed in 353 BC, 217 BC, 212 BC (during the Second Punic War) and in 87 BC (during the civil war between Marius and Sulla).
Throughout the entire span of the walls was used the same building technique, consisting of alternating courses of stone blocks (approximately 59 cm high, or 2 Roman feet). The structure reached a height of approximately 10 m and a width of 4 m. The blocks were certainly laid by different teams of stonemasons working at the same time on stretches of 40 m, for the points in which the work of two teams meet never match exactly.

On the stone blocks are visible many carved signs, which have been interpreted as individual markings used regularly by the stonemasons to check the accuracy of their work. The walls had a total length of almost 11 km and encircled an area of approximately 426 ha.