City on the Adriatic Sea in northern Italy which became a Roman city in 49 BC and the base of Adriatic fleet. The earliest inhabitants of Ravenna were probably Italic peoples who moved southward from Aquileia about 1400 BC. According to tradition, it was occupied by the Etruscans and later by the Gauls. It was selected by Roman Emperor Honorius as his capital in 402 AD because of its security. Ravenna was important in history as the capital of the Western Roman Empire in the 5th century AD and later (6th-8th century) of Ostrogothic and Byzantine Italy. During Theodoric's reign (498-526), the emperor constructed new churches and public buildings, decorated in styles that blended the Eastern and Western art styles of the time. The mosaics inside the buildings are the finest collection anywhere in the Byzantine world, and were extremely influential in determining art styles throughout much of Europe and the East in the early Middle Ages. One of the earliest of Ravenna's extant monuments is the mausoleum of Galla Placidia, built in the 5th century AD by Galla Placidia, the sister of the emperor Honorius.