The Kostel castle belongs among the oldest and most important cultural- historical monuments in the municipality Kostel. It was first documented the 14th century. It was occupied in the 16th century by the Turks, who deceived the castle's inhabitants by dressing up as Croatian peasants. The plot of land includes the castle, the settlement and the Gothic church of the Three Kings. The castle offers magnificent view on the surroundings and the valley of the river Kolpa. The castle is being temporarily renovated.