of the collapse of the remaining structures on the edge of the cliff. The vegetation that proliferates on the cliff has limited the progression of the rain-wash effect but causes the break-up of the masonry structures. The World Monuments Fund included Kilwa on its 2008 Watch List of 100 Most Endangered Sites, and since 2008 has been supporting conservation work on various buildings. In 2014 it was removed from the list. Between 2005 and 2009, the Zamani Project documented some of the Swahili ruins on Kilwa Kisiwani with terrestrial 3D laser scanning. The structures documented include: the Gereza (prison); the Great Mosque; the Husuni Kubwa; the Makutani Building and the Malindi Mosque. Some of the 3D models, a panorama tour, elevations, sections and plans are available on www.zamaniproject.org. Historic Buildings Great Mosque The Great Mosque of Kilwa is a congregational mosque on the island of Kilwa Kisiwani, in Tanzania. It was likely founded in the tenth century, but the two major stages of construction date to the 12th or twelfth and thirteenth century, respectively. It is one of the earliest surviving mosques on the Swahili Coast. The smaller northern prayer hall dates to the first phase of construction. It contained a total of 16 bays supported by nine pillars, which were originally carved from coral but later replaced by timber. The structure was entirely roofed, and was perhaps one of the first mosques in the area to have been built without a courtyard. In the early fourteenth century, Sultan al-Hasan ibn Sulaiman, who also built the nearby Palace of Husuni Kubwa, added a southern extension which included a great dome. This dome was described by Ibn Battuta after he visited Kilwa in 1331. You can view a 3D model of the Great Mosque here Palace of Husuni Kubwa Husuni Kubwa (the "Great Palace"), situated outside the town, was an early 14th-century sultan's palace and emporium. Other defining features include causeways and platforms at the entrance of the Harbour made from blocks of reef and coral nearly a meter high. These act as breakwaters, allowing mangroves to grow which is one of the ways the breakwater can be spotted from a distance. Some parts of the causeway are made from the bedrock, but usually the bedrock was used as a base. Coral stone was used to build up the causeways with sand and lime being used to cement the cobbles together.