Constantine, AE Follis, Rome. 317 - 318 AD.
	
obv: IMP CONSTANTINVS P F AVG, laureate, draped and cuirassed bust right.
rev: SOLI INV-I-CT COM DN, Sol standing half-left, chlamys 
across left shoulder, holding Victory on globe and raising right hand.
Left field: X.
Right field: Crescent
Mintmark RT.

RIC VII Rome 49 var (reverse field mark X instead of star)

Courtesy of Forvm Ancient Coins online store, item 20486.