Koznik, Medieval castle in Brus, Serbia

Koznik is a medieval fortress on a conical hill at 921 m above the Rasina river, 8 km west of Aleksandrovac. Its irregular polygonal walls, 58 m long and 44 m wide, are reinforced by eight square towers; the northern donjon tower has a 9 m square base and 2 m thick walls. The southern, lower section holds a cistern with four filter wells.

Prince Lazar built the castle in the 14th century as a defensive fortress to control the Rasina River Valley and the Zupa region. The structure served a strategic role in protecting these important areas.

Each year on 9 August, the feast of Saint Pantaleimon, a folk gathering and an art and poetry colony are held at Koznik. The castle area is also linked in epic poetry to Radič Postupović, sung as Rade Oblačić or Rajko od Rasine.

Visitors reach the fortress through hiking trails from Koznica village, with the ascent taking about 45 minutes. The terrain is hilly and requires proper footwear and plenty of water, especially on warmer days.

In the southern, lower part of the fort stands a cistern 5 metres across, with four filter wells. When archaeologists uncovered it in the 1970s, clear water was still inside, showing the rainwater system worked centuries after abandonment.