During the Early Middle Ages, Byzantine/Eastern Roman Empire was more advanced than Western Europe. The Byzantines continued to practice Roman culture while most of Western Europe reverted from Roman influence. Classical writings were preserved and copied by Byzantine scholars. Byzantine science was a continuation of Classical Science and it was closely connected with ancient pagan philosophy and metaphysics. They made great innovation in areas of physics, mathematics, and medicine. Byzantines also made advances in architecture such as Cross in Square, Pendentive Dome, and Pointed Arch Bridge. Byzantines had advanced military technology such as the counterweight trebuchet, Greek Fire and incendiary grenades. Their city of Constantinople was protected by the Theodosian Walls which protected them from sieges until the Ottoman Conquest in 1453.