On the reverse of a bronze coin dated to the time of the Roman emperor Caracalla (188-217 AD), Ares is depicted fully armed. He wears a helmet, breastplate, short chiton and shin guards. He holds a round shield in his right hand and a spear in his left. Around Ares there is an inscription of the ethnic name of the Serdika citizens (CΕΡΔΩΝ).

On the obverse side, the portrait of the emperor Marcus Aurelius Pius Severus Antoninus, known as Caracalla, is depicted. There is also an inscription of his name (ΑVΤ Κ Μ ΑVΡ ϹΕV ΑΝΤΩΝΕΙΝΟϹ).

Serdika was an important Roman city, crossed by the river Strymon. Sofia, the capital of Bulgaria, was built there later.