Septimius Severus AE17 of Nikopolis ad Istrum. 

AV KAI CE CEVHROC, laureate head right.
NIKOPOLITWN PROC ICTRW, serpent-entwined tripod altar. 

Varbanov 2330. 

Note: Varbanov lists 11 different coins with this reverse,
with different obverse and reverse legends, and bust types.