There are many tall old buildings in 'Asir, each of which is called a fort or a qasaba, they are built of mud or stones or both, and their entrances are designed in a tight way that makes it difficult to storm them. The book aims to highlight the military architectural heritage in the 'Asir region, represented by military fortifications in civil buildings such as fortified palaces, castles and forts that the 'Asir people used for housing, defense and surveillance. The scientific approach that the book follows is represented by the descriptive approach to these buildings on the one hand and the analytical and comparative approach to the defensive architectural elements in contemporary fortified palaces, castles and forts on the other hand.The book also discusses the styles of castles, forts and military architectural structures that were established during the Ottoman era, these castles and forts were built by local residents and with local materials of stones and clay, their style was formed according to the prevailing styles of military fortifications in that region, these castles were built on the foundations of castles that preceded the Ottoman era.