Sack of Rome (410) - Wikipedia

On August 24, 410, Rome was overrun by the Visigoths under Alaric I for the first time in nearly 800 years. It is seen as the fall of the Western Roman Empire. From the article:

"The Sack of Rome occurred on 24 August 410. The city was attacked by the Visigoths led by King Alaric. At that time, Rome was no longer the capital of the Western Roman Empire, having been replaced in that position first by Mediolanum in 286 and then by Ravenna in 402. Nevertheless, the city of Rome retained a paramount position as "the eternal city" and a spiritual center of the Empire. The sack was a major shock to contemporaries, friends, and foes of the Empire alike."