One of the characters I most enjoyed creating in my novel Total War Rome: The Sword of Attila was Gnaeus Uago Alentius, a senior tribune of the fabri – the Roman equivalent of the Corps of Engineers – who oversees a military mapping unit in Rome. I'd imagined that by the 5th century AD, Roman proficiency in field survey and road-tracing might have led to a kind of topographical department in the army, with the fabri close to creating detailed maps akin to the early British Ordnance Survey series - something that would have been halted by the collapse of the Roman army in the west shortly afterwards, leaving us no evidence of their work ...