Soko Grad, also known as Sokolac, is a medieval city and fortress 2 km east of the spa town of Sokobanja, Serbia. The fortress was declared a Monument of Culture of Great Importance in 1982, and it is protected by Republic of Serbia. The fortress was founded in the 6th century during the reign of Eastern Roman Emperor Justinian I, to prevent incursions of Pannonian Avars and Slavs into Balkan peninsula. In 1172, it was occupied by Stefan Nemanja and became part of the medieval Serbian state. During the expulsion of the Bogomils from Serbia, Nemanja had a clash with the administrator of Soko, who was a Bogomil himself. Ottoman Empire occupied it in the year 1398.