Constantinople (see other names) became the capital of the Roman Empire during the reign of Constantine the Great in 330. Following the collapse of the Western Roman Empire in the late 5th century, Constantinople remained the capital of the Eastern Roman Empire (also known as the Byzantine Empire; 330–1204 and 1261–1453), the Latin Empire (1204–1261), and the Ottoman Empire (1453–1922). Following the Turkish War of Independence, the Turkish capital then moved to Ankara. Officially renamed Istanbul in 1930, the city is today the largest city and financial centre of Turkey. It is also the largest city in Europe. In 324, after the Western and Eastern Roman Empires were reunited, the ancient city of Byzantium was selected to serve as the new capital of the Roman Empire, and the city was renamed Nova Roma, or 'New Rome', by Emperor Constantine the Great. On 11 May 330, it was renamed Constantinople and dedicated to Constantine. Constantinople is generally considered to be the center and the "cradle of Orthodox Christian civilization". From the mid-5th century to the early 13th century, Constantinople was the largest and wealthiest city in Europe. The city became famous for its architectural masterpieces, such as Hagia Sophia, the cathedral of the Eastern Orthodox Church, which served as the seat of the Ecumenical Patriarchate; the sacred Imperial Palace, where the emperors lived; the Hippodrome; the Golden Gate of the Land Walls; and opulent aristocratic palaces. The University of Constantinople was founded in the 5th century and contained artistic and literary treasures before it was sacked in 1204 and 1453, including its vast Imperial Library which contained the remnants of the Library of Alexandria and had 100,000 volumes. The city was the home of the Ecumenical Patriarch of Constantinople and guardian of Christendom's holiest relics such as the Crown of thorns and the True Cross. Constantinople was famous for its massive and complex fortifications, which ranked among the most sophisticated defensive architecture of antiquity.