Zagorje ob Savi is a town and a municipality in central Slovenia. It is located in the valley of Medija Creek, a minor left-bank tributary of the Sava River, 52 km (32 mi) east of Ljubljana 36 km (22 mi) southwest of Celje, and 6 km (4 mi) west of Trbovlje. Traditionally the area was part of the Upper Carniola region. The entire municipality is now included in the Central Sava statistical region. The town is home to about 7,000 people and the population of the municipality is about 17,000.
Archaeological evidence shows that the area was already settled in the Late Bronze Age and Iron Age. Zagorje was first mentioned as Sagor in written records of the Patriarchate of Aquileia dating to 1296. In written form it later also appears as Zaegor, Sager, Seger, and Cagoer. In 1755 deposits of coal were discovered in the area and the town's economic development began. Coal mining was one of the area's main activities until 1995, when the last mines were closed. In 2010, Zagorje ob Savi was heavily affected by floods.
The parish church in the settlement is dedicated to Saints Peter and Paul and belongs to the Roman Catholic Archdiocese of Ljubljana. It is a Neo-Romanesque church built in 1873.