Mountain Rtanj is located on the northern edge of the Sokobanja valley. The legend of an extinct volcano, fireballs, as rare natural phenomena, pits, caves, steep peaks, endemic plants, stories about aliens and other mysteries attract a large number of mountaineers, nature lovers, scientists and treasure hunters. A special challenge is an ascent to the top of Rtanj (Šiljak 1560 m), from where the view reaches as far as the confluence of the Sava and the Danube. Numerous adventurers are also attracted by the ice cave, 50 m deep, which is located in the area of ​​the village Mužinac. There are the remains of the church-chapel of St. George on Šiljak. The church was in 1935. erected by Greta Minch, in memory of her husband Julius Minch, owner of the Rtanj mine.