It's a city commemorative like these, but I can't make out the mint on your coin: CONSTANTINOPOLIS COMMEMMORATIVE AE3/4 OBVERSE: CONSTANTINOPOLI, laureate, helmeted & mantled bust left holding scepter REVERSE: Victory standing left, foot on prow with sceptre and leaning on shield, CONS Gamma in ex. Struck at Constantinople, 330-33AD 2.2g, 15mm RIC VII 63 CONSTANTINOPOLIS COMMEMMORATIVE AE3/4 OBVERSE: CONSTAN TINOPOLIS, laureate, helmeted & mantled bust left holding sceptre REVERSE: Victory standing left on foot of prow with sceptre and leaning on shield, •BSIS• in ex. Struck at Siscia , 334-335 AD 2.39g, 17mm RIC 241 CONSTANTINOPOLIS COMMEMMORATIVE AE3/4 OBVERSE: CONSTANTINOPOLIS, crested, laureate helmeted bust of Constantinopolis left in imperial mantle & holding sceptre REVERSE: Victory with open wings standing left, right foot on a vessel's prow holding sceptre & leaning on shield. Mintmark SMTSD Struck at Thessalonica , 330-33 AD 2.3g 18mm RIC VII 188
The mintmark is unclear, but it is not from the four mints around the Bosporus (Heraclea, Constantinople, Nikomedia, Cyzicus) which used the spelling CONSTANTINOPOLI, omitting the terminal "S" found elsewhere and which is on your coin. Here is a CONSTANTINOPOLI coin from Heraclea: