In addition to this civic infrastructure the design of the kasbah appears to have an emphasis on protective fortifications – even by the standards of previous royal citadels. Its outer defensive walls (built in rammed earth) were an astonishing 7 meters thick and its angles or corners were typically fortified with massive bastions (such as Borj Belkari).[1][2] Especially near the old city, the kasbah and its palaces were protected by two or more lines of defensive walls.[19] Roads and bridges also connected every area, allowing for easier troop movement.[19] The many massive granaries and storage facilities (such as the Heri es-Souani and the so-called Qara "Prison") for food and supplies were also designed to allow the kasbah's inhabitants to survive a long siege, with Moulay Isma'il reportedly claiming his citadel could hold out for ten years under siege.[19] Despite this emphasis on defense, the Kasbah was never submitted to a real siege in Isma'il's time.[19]