 The Servian Wall around Rome was an ambitious project of the early 4th century BC.The wall was up to 10 metres (32.8 ft) in height in places, 3.6 metres (12 ft) wide at its base, 11 km (7 mi) long, and is believed to have had 16 main gates, though many of these are mentioned only from writings, with no other known remains.Some of it had a "fossa" or ditch in front, and an agger behind, and it was enough to deter Hannibal.