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. Brick and stone In addition to rammed earth, brick and (especially in desert regions) mudbrick were also common types of materials for the construction of houses, civic architecture, and mosques. Many medieval minarets, for example, are made in brick, in many cases covered with other materials for decoration. Stone masonry was also used in many notable monuments, especially in the Almohad period. The monumental Almohad gates of Bab Agnaou, Bab er-Rouah, and the main gate of the Udayas Kasbah (Bab Oudaia) made extensive use of carved stone. The major Almohad minarets of the same period demonstrate the relative variability in construction material and methods, depending on the region and the demands of the structure: the minaret of the Kutubiyya Mosque is built in rubble masonry using sandstone, the Giralda of Seville (in Spain) was made in local brick, the massive but unfinished Hassan Tower in Rabat was made in stone, and the minaret of the Kasbah Mosque in Marrakesh was made with a base of rubble stone and a main shaft of brick. Wood Wood was also extensively used, but mostly for ceilings and other elements above eye level such as canopies and upper galleries. Many buildings such as mosques and mausoleums have sloped wood-frame or artesonado-like ceilings, known locally as berchla or bershla, often visually enhanced by the use of geometric patterns in their arrangement, sculpting, and painted decoration. Many doorways, street fountains, and mosque entrances are also highlighted with sculpted wood canopies which were characteristic of Moroccan and Moorish architecture. Especially from the Marinid period onward, sculpted wood became a major component of architectural decoration. Wood generally came from Moroccan cedar trees, still highly valued today, which once grew abundantly on mountain slopes across the country but are now partly endangered and limited to forests of the Middle Atlas. Other types of wood were still occasionally used, however. The