Olesko Castle is located within the borders of the present-day Busk Raion in Ukraine. The first historical records of the castle are in a document dated 1390, when Pope Boniface IX gave Olesko and Tustan to a Catholic bishop of Halych. It is located about seventy-five kilometers from Lviv, the largest city in western Ukraine.

Olesko Castle, oval in shape, stands on top of a small hill, about fifty meters in height. A moat and a wall surrounds it, which serves as a defence for the castle. The castle is also surrounded by a dense swamp. The land that the castle sat on changed ownership many times. It was originally on the border of land of Volhynia and land of Lviv.

The castle was, at different times, owned by Poland, Lithuania, and Hungary. It became a political landmark in the 14th century when movable borders between the three aforementioned countries ran through its territory. Battles for ownership of the castle were constant. A deep well in the basement of the castle was used as an escape route for besieged prisoners.