Constantine II, AE follis, Rome. AD 318-319. 

CONSTANTINVS IVN NOB C, laureate, draped, cuirassed bust right.
VIRTVS AVGG, campgate with six layers, three turrets, closed 
doors. 
P-R across fields. 

Mintmark RQ. 

RIC VII Rome 183.

Ex-Gorny & Mosch, March 2013.