Aurelian AE Antoninianus. Serdica, AD 274-275. 

IMP CL DOM AVRELIANVS PF AVG, radiate, cuirassed bust right.
SOLI INVICTO, Sol, holding whip and raising right hand, walking left, treading down one of two captives.

Mintmark XXI dot T.

RIC V-1, 311 Serdica var (bust type and Sol's attribute).

Very rare.

With permission of cngcoins.com