Constantinople was the capital city of the Roman/Byzantine Empire, and also of the brief Latin, and the later Ottoman empires. It was reinaugurated in 324 AD from ancient Byzantium as the new capital of the Roman Empire by Emperor Constantine the Great, after whom it was named, and dedicated on 11 May 330 AD.
From the mid-5th century to the early 13th century, Constantinople was the largest and wealthiest city in Europe. It was instrumental in the advancement of Christianity during Roman and Byzantine times as the home of the Ecumenical Patriarch of Constantinople and as the guardian of Christendom's holiest relics such as the Crown of Thorns and the True Cross. After the final loss of its provinces in the early 15th century, the Byzantine Empire was reduced to just Constantinople and its environs, along with Morea in Greece, and the city eventually fell to the Ottomans after a 53-day siege on 29 May 1453.
Constantinople was famed for its massive and complex defences.