Constantine I, AE Follis. 

Obv: CONSTAN-TINVS AVG, laureate head right 
Rev: PROVIDEN-TIAE AVGG, campgate with 2 turrets,  6 layers, star above, 
 no doors. 
Mintmark STR(dot-in-crescent). 

RIC VII Trier 475, rated C3.

Contributed by Dane for George Clegg (biggyg2), October 2007