Constantine II, AE Follis, 324-325 AD. 

CONSTANTINVS IVN NOB C, laureate, draped, cuirassed bust left
PROVIDEN-TIAE CAESS, campgate, 2 turrets, 6 layers, 
star above, no doors. 

Mintmark PTR in ex. 

RIC VII Trier 455, rated C1

Used with permission of Roma Numismatics, October 2009