Constantine I AE Follis. 307-312 AD. 

Obv: IMP CONSTANTINVS PF AVG, laureate, draped & cuirassed bust right, 
 seen from back 
Rev: MARTI CON-SERVATORI, Mars standing right in military dress, leaning on 
 reversed spear & left hand on shield; T-F across fields; mintmark PLN in ex. 

RIC VI London 119. 

(This bust type, seen from the back, is not listed in RIC for this series), rated rare

Contributed by Dane for TimeLine Originals, December, 2008.