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

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

Mintmark MN delta. 

RIC VII Nicomedia 128 var (no dot at the end of the rev. legend)