Middle Byzantine art flourished between the 6th and 15th centuries and was characterized by elaborate mosaic and fresco works in churches and monasteries. Icons of Christ and the Virgin Mary produced in the 6th century at Sinai monastery were a central part of personal devotion but also sparked iconoclasm debates between the 8th-9th centuries over whether icon veneration constituted idol worship. Major artistic centers included the Hagia Sophia and Hosios Loukas monasteries, known for their mosaic domes and architectural innovations that influenced Byzantine and post-Byzantine Orthodox church design.