Serbian Carpathians is a mountain range in eastern Central Serbia, located in Central Europe. It presents an extension of proper Carpathian Mountains across the Danube, connecting them with the Balkan Mountains in the southeast. They stretch in north–south direction in eastern Serbia, east of the Great Morava valley and west of the White Timok Valley and north of the Nišava Valley. The mountains are 800–1500 m high, and dominated by karst limestone geologic features, the highest one being Rtanj Mountain.

Rtanj is a mountain situated in eastern Serbia, approximately 200 km southeast of Belgrade, between the towns of Boljevac on north and Sokobanja on the south. It belongs to the Serbian Carpathians. Its highest peak is Šiljak, a natural phenomenon of karst terrain.