Constantius II, AE follis. Nicomedia. AD 325-326. 

FL IVL CONSTANTIVS NOB C, laureate, draped and cuirassed bust left.
PROVIDEN-TIAE CAESS dot, campgate with seven layers, two turrets, star above, no doors. 

Mintmark MNB. 

RIC VII Nicomedia 128; Sear 17648.