Preservation. Most surviving medieval Muslim buildings are masjids (mosques). As with churches and cathedrals in Europe and the temples of ancient civilizations, Muslim religious buildings have survived in better condition and in far greater numbers than Muslim secular structures. The much higher survival rate for masjids than secular buildings may be attributed to several factors. It is suggested in the Qur'an (22: 40 and 72: 18) and established in Muslim law that once a masjid has been used for worship, it should never be alienated, sold, or turned to any other purpose. Furthermore, because of the respect people have for houses of worship in general, they tend to invest more money in them and build them with better materials and better engineering than secular structures. As a result, people feel obliged to spend more effort maintaining them as significant investments and cultural artifacts. Masjids...