The Drencova/Dranko fortress is located 2 km downstream of Berzasca, today in the middle of the Danube. It was a border fortress, built around 1419. Between 1429-1435 was the property of the order of the Teutonic knights and of Iancu of Hunedoara’s family  in 1457. As a border fortress, it has been attacked several times and even destroyed by Turks. Old documents refer to the dimensions of the city walls that would have been 20-25 m long, 15 m high, and 1,5 m thick. After the construction of the iron gate hydroelectric power plant, the ruins were surrounded by the waters of the Danube and have since been continually washed away by them, gradually eroded by the water course and their freezing and thawing, most likely to be condemned to vanish.