The Roman bridge across the River Marecchia, once called the Arimnus, around which the earliest settlement grew, still links the city centre and the suburb of Borgo San Giuliano. It was from here that two Roman consular roads started. The Via Aemilia, built in 187 BC by Consul Aemilius Lepidus, linked Rimini to Piacenza. The Via Popilius led to Ravenna, continuing to Aquileia.

The bridge, started under Caesar Augustus in 14 AD and completed by Tiberius in 21 AD, as confirmed by the inscriptions on the inside of the parapets, is remarkable for its architectural design, its massive structures and its construction methods. The little space dedicated to decoration is rich however in symbolic meanings.

Made in Istrian limestone, the bridge has five arches built on robust piers with breakwaters set obliquely to reduce resistance to the flow of the river.

Recent inspections have shown that the piers rest on a system of wooden piles that is still in efficient working order.

Over the centuries the bridge has endured many episodes that threatened its survival, from earthquakes to floods, and from wear and erosion to battles, like the attack made on it by Narses in 551 during the war between the Byzantines and the Ostrogoths.