sentences:  The fortifications with massive walls, thick and high, were built around the town on the south bank of the river in 320–330 under Constantine the Great, seemingly for immigrant "barbarians" (foederati) as part of the policy of pacifying them.However, the walls could not withstand the destruction of the city in the Gothic Wars in 376–8, in 447 by the Huns, and in the 480s again by the Goths.Each time it was rebuilt, and in the 5th–6th centuries Abritus was one of the largest cities in the province and seat of a bishop.