Mosalla Hill is one of the historical hills in Hamadan. Since in the past, prayers of two feasts were said on this hill, it is called Mosalla. It appears that this hill is located along with Sang-e Shir Hill and Hegmataneh Hill and these hills had been connected. As some historians believe, this hill has flourished in pre-Islamic periods and it has had a fort the ruins of which have remained. Although some pundits believe that Median had been on this hill, in Parthian Period, Mosalla Hill had been a fortress hill and some artifacts found from that period confirm this issue.