Constantinople became the new capital of the Roman Empire in the East on May 11, 330 AD and continued as such for 1123 years. Emperor Constantine spent four years building his city on the site of Byzantium, which itself was established in 658 BC. Constantinople was built on seven hills above the Bosporus, dominating the entrance to the Black Sea. It was one of the premier European cities during the Medieval period. It's fortifications were immense. Bubonic plague struck Constantinople in 541 and 732. Beginning in the 700s, attacks by Moslems and Turks gradually wore down the Byzantines. The city was conquered in 1204 by Crusaders, urged on by Alexius, son of the deposed Byzantine emperor Isaac II Angelusto, who then overthrew the usurper Alexius III. But the Byzantines were shoved aside and the city became the center of a Latin Empire from 1204–1261. This feudal kingdom consisted of lands in the south Balkans and Greece. Rule was divided between the Crusaders and the Venetians (who supplied the ships for the crusade). The empire quickly fell apart because of internal bickering and attacks by the Bulgars, Turks, and Greek states of Nicaea and Epirus. The city was retaken in 1261 by Michale VIII of Nicaea, who restored the Byzantine Empire. Venice retained most of the Greek Isles, the French Villehardouin family kept Achaia, and Athens became part of the Catalan kingdom. The Turks took the city in 1453 and built it into an even more splendid city. The name wasn't changed until 1930, when it became Istanbul.