Constantine II, Rome, AE 3. 318-319 AD. 21 mm, 3.5 g.

CONSTANTINVS IVN NOB C, Laureate, draped, cuirassed bust right.
ROMAE AETERNAE, Roma seated right on shield, inscribing X-V on shield on her lap. 
P-R across fields. 
Mintmark RS.

RIC VII Rome 156.

With permission of vauctions.com, July 2011.