Aquincum was originally settled by the
Eravisci, a
Celtic tribe. Aquincum served as a military base (
castrum), having been part of the Roman border protection system called
limes. Around AD 41–54, a 500-strong cavalry unit arrived, and a
Roman legion of 6,000 men (
Legio II Adiutrix) was stationed there by AD 89. The city gradually grew around the fortress, and after Pannonia was reorganised by the Romans in AD 103, Aquincum became the capital city of the Roman province of
Pannonia Inferior until the administrative reform of
Diocletian more than a century later. Under
Hadrian, the city obtained municipal status, while under
Septimius Severus, Aquincum became a
colonia. As the centre of operations on the Roman frontier against the neighbouring
Iazyges, Aquincum was occasionally the headquarters of emperors. The
decline of the Roman Empire also affected Aquincum, and the ancient city was largely destroyed by 350 AD.
Germans and the
Huns invaded the region during 409 AD. == Settlement buildings ==