<P> The city provided a defence for the eastern provinces of the old Roman Empire against the barbarian invasions of the 5th century . The 18 - meter - tall walls built by Theodosius II were, in essence, impregnable to the barbarians coming from south of the Danube river, who found easier targets to the west rather than the richer provinces to the east in Asia . From the 5th century, the city was also protected by the Anastasian Wall, a 60 - kilometer chain of walls across the Thracian peninsula . Many scholars argue that these sophisticated fortifications allowed the east to develop relatively unmolested while Ancient Rome and the west collapsed . </P> <P> Constantinople's fame was such that it was described even in contemporary Chinese histories, the Old and New Book of Tang, which mentioned its massive walls and gates as well as a purported clepsydra mounted with a golden statue of a man . The Chinese histories even related how the city had been besieged in the 7th century by Muawiyah I and how he exacted tribute in a peace settlement . </P> <P> The Byzantine Empire used Roman and Greek architectural models and styles to create its own unique type of architecture . The influence of Byzantine architecture and art can be seen in the copies taken from it throughout Europe . Particular examples include St Mark's Basilica in Venice, the basilicas of Ravenna, and many churches throughout the Slavic East . Also, alone in Europe until the 13th - century Italian florin, the Empire continued to produce sound gold coinage, the solidus of Diocletian becoming the bezant prized throughout the Middle Ages . Its city walls were much imitated (for example, see Caernarfon Castle) and its urban infrastructure was moreover a marvel throughout the Middle Ages, keeping alive the art, skill and technical expertise of the Roman Empire . In the Ottoman period Islamic architecture and symbolism were used . </P> <P> Constantine's foundation gave prestige to the Bishop of Constantinople, who eventually came to be known as the Ecumenical Patriarch, and made it a prime center of Christianity alongside Rome . This contributed to cultural and theological differences between Eastern and Western Christianity eventually leading to the Great Schism that divided Western Catholicism from Eastern Orthodoxy from 1054 onwards . Constantinople is also of great religious importance to Islam, as the conquest of Constantinople is one of the signs of the End time in Islam . </P>

Who ruled constantinople for 50 years during the early 1200s