The solidus was coined for the first time in the year 301 AD by Emperor Diocletian to replace the old aureus. Constantine I improved its purity and weight (4.5g of gold per piece) and, since the year 312 AD, the solidus became the official state currency. It was with this coin that legal fines and payments to civil servants and soldiers were settled. Thus, the Latin word solidus is the root of the more generic term “sou” in Catalan, today meaning salary or wage.

On the obverse, laureate, draped and cuirassed bust of Constantine I, surrounded by the legend D(ominus) N(oster) CONSTANTINVS IVN(ior) NOB(ilissimus) CAES(ar) and a beaded rim. On the reverse, Constantine II dressed as a soldier, with a standard in his right hand and a long sceptre in his left, before two other military standards. Surrounding the figure, the legend PRINCIPI IVVENTVTIS and a beaded rim. On the exergue, SIRM(ium).

Minted by Constantine I, Roman emperor, in honour of his first born, Constantine II. Sirmium, known today as Sremska Mitrovica.

Sirmium (Sírimum). 320-321 dC

Weight: 4,26 g