Rome is sacked by Alaric the Visigoth
Although Rome, as a capital city, had long ceased to have any real significance in practical terms, its fall to a tribe of barbarians marks the irrevocable decline of the Roman Empire in the West. Western Roman Emperors continue to be appointed for the next sixty years, but they have little real standing.
Construction of Constantinople’s triple walls begin
Although commonly known as the "Theodosian Walls" after Theodosios II, the reigning emperor), the walls were actually built on the orders of Anthemius, the Empire’s Prefect of the East, to counter an immediate threat from the Huns.
In conjunction with Constantinople's naturally strong location, the Theodosian walls will prove their worth against any number of attacks upon Constantinople through Byzantine history. They will fall to an attacking army only twice, once during the chaos of the Fourth Crusade (1204) and, finally, to the Ottoman Turks, who breach them in 1453 with the help of artillery and overwhelming numbers.
Rome is sacked for the second time.
This time, in a very systematic and controlled manner, by the Vandals – another tribe of Germanic barbarians. The Vandals go on to establish a kingdom in the Roman provinces of North Africa, whilst the Goths establish themselves in Italy and Spain.