Art produced in the Byzantine empire (or Eastern Roman Empire)—at its height, a territory that spanned large swaths of the Mediterranean, present-day Turkey, Southern Spain, and Italy—between the 4th and 15th centuries, when it fell to the Ottoman Turks. As the empire's official religion was Orthodox Christianity, Byzantine art was largely devotional, Christian art. Perhaps the best known example of Byzantine art is a tenth-century mosaic of the Virgin Mary in the Hagia Sophia in Istanbul that demonstrates the stylized forms, sharp contours, flat fields of color, and gold mosaic the period is known for. Byzantine icons of Mary (icons were traditional wood panels that included portraits or stories of holy figures, meant for veneration) set a benchmark for Christian art far and wide: in the 13th and 14th centuries Italian artists drawing on Byzantine icons, exemplified by Giotto’s Madonna and Child, launched the birth of panel painting, a format that became central to Western art making. Byzantine art also flourished in a wide variety of media including glass mosaic, panel and wall painting, metalwork and enamel, and carved relief in ivory and other precious materials.