The Punic Carthage was divided into four equally sized residential areas with the same layout, had religious areas, market places, council house, towers, a theater, and a huge necropolis; roughly in the middle of the city stood a high citadel called the Byrsa. Surrounding Carthage were walls "of great strength" said in places to rise above 13 m, being nearly 10 m thick, according to ancient authors. To the west, three parallel walls were built. The walls altogether ran for about to encircle the city. The heights of the Byrsa were additionally fortified; this area being the last to succumb to the Romans in 146 BC. Originally the Romans had landed their army on the strip of land extending southward from the city.