instructing others in those branches of the profession in which he had distinguished himself. At various locations described by Vitruvius, battles and sieges occurred. He is the only source for the siege of Larignum in 56 BC. Of the battlegrounds of the Gallic War there are references to: The siege and massacre of the 40,000 residents at Avaricum in 52 BC. Vercingetorix commented that "the Romans did not conquer by valour nor in the field, but by a kind of art and skill in assault, with which they [Gauls] themselves were unacquainted." The broken siege at Gergovia in 52 BC. The circumvallation and Battle of Alesia in 52 BC. The women and children of the encircled city were evicted to conserve food, and then starved to death between the opposing walls of the defenders and besiegers. The siege of Uxellodunum in 51 BC. These are all sieges of large Gallic oppida. Of the sites involved in Caesar's civil war, we find the Siege of Massilia in 49 BC, the Battle of Dyrrhachium of 48 BC (modern Albania), the Battle of Pharsalus in 48 BC (Hellas – Greece), the Battle of Zela of 47 BC (modern Turkey), and the Battle of Thapsus in 46 BC in Caesar's African campaign. A legion that fits the same sequence of locations is the Legio VI Ferrata, of which ballista would be an auxiliary unit. Mainly known for his writings, Vitruvius was himself an architect. In Roman times architecture was a broader subject than at present including the modern fields of architecture, construction management, construction engineering, chemical engineering, civil engineering, materials engineering, mechanical engineering, military engineering and urban planning; architectural engineers consider him the first of their discipline, a specialization previously known as technical architecture. In his work describing the construction of military installations, he also commented on the miasma theory – the idea that unhealthy air from wetlands was the cause of illness, saying: Frontinus mentions Vitruvius in connection with the standard sizes of pipes: the role he is most widely respected. He is often credited as father of architectural acoustics for describing the technique of echeas placement in theaters. The only building, however, that we know Vitruvius to have worked on is one he tells us about, a basilica completed in 19 BC. It was built at Fanum Fortunae, now the modern town of Fano. The Basilica di Fano (to give the building