The town walls were built during the first years of the Roman presence in Tàrraco (late third century-early second century BC). Only a part of the original enclosure has been preserved, that located in the Upper Part of the town. The same building techniques were used on the walls and towers: megalithic rocks were used as a base for paraments made of ashlars, which were usually bossed. Three towers remain today: the Capiscol Tower, the Archbishop Tower (with major medieval modifications) and the Minerva Tower (the most authentically Roman). In the megalithic socle there are small "portelles", or gateways for pedestrians. Only one of the main gates remains today, that near the Minerva Tower, which has undergone many modifications over the centuries.