Constantine I, AE follis, London. 

CONSTANTINVS P F AVG, laureate and cuirassed bust right.
PRINCIPIA I-VVENTVTIS, Prince standing left, in military 
dress, holding spear and resting on shield.
Crescent in left field. 
Mintmark PLN. 

RIC VII London 132.
Extremely rare.

With permission of ArtCoins Roma, Auction 6, Dec. 2012.