Constantine I AE Follis. 

Obv: CONSTAN-TINVS AVG, laureate head right 
Rev: PROVIDEN-TIAE AVGG, campgate, 2 turrets, 7 layers, star above, no doors, 
 BSIS in ex. 

RIC VII Siscia 183, rated R3.

Contributed by Dane for Joe Guerra, USA, December, 2008.