Islamic architecture originated from Roman, Byzantine, and Persian influences and spread throughout the Islamic world. It includes mosques, tombs, palaces, and forts and is characterized by courtyards, hypostyle halls, vaulting, muqarnas, and geometric and floral ornamentation. Major architectural features include domes, arches, arabesque patterns, and calligraphy. Early influences included the Dome of the Rock and Great Mosque of Damascus, which incorporated Byzantine elements. Regional variations emerged, with Eastern styles featuring non-radial vaulting and the West utilizing horseshoe arches.