Gordian III and Serapis. AE26, Pentassarion, Markianopolis, Moesia.

AVT K M ANT GORDIANOC AVG, laureate, draped bust of Gordian
right, facing draped bust of Serapis left, modius on head.
YP MNOFILOY MARKIANOPOLITWN, Triumphal arch with three
portals, surmounted by three statues. E in doorway.

Varbanov 1945 (this coin), otherwise unlisted. 
With permission of Ray Wilk, 2009.