This type of construction required consistent maintenance and upkeep, as the materials are relatively permeable and are more easily eroded by rain over time; in parts of Morocco, (especially near the Sahara) kasbahs and other structures made with a less durable composition (typically lacking lime) can begin to crumble apart in less than a couple of decades after they've been abandoned. As such, old structures of this type remain intact only insofar as they are continuously restored; some stretches of wall today appear brand new due to regular maintenance, while others are crumbling.