The City municipality of Kostolac (Serbian Cyrillic: Градска општина Костолац, romanized: Gradska opština Kostolac is a town in Serbia and one of two city municipalities which constitute the City of Požarevac. It is situated on the Danube river. The remains of Viminacium, the capital of the Roman province of Moesia Superior, are located near Stari Kostolac some 2 km to the east of Kostolac. Kostolac is also a center of area called Stig and home of thermal power plants and coal mines.