The fortress or the Old Town was first mentioned in the 14th century as a center where many famous people came, because it was an extremely representative building, and in the 16th century it was repurposed as a place for protection from the Turks. Today, almost nothing remains of the fort, the best preserved is the Chapel of the Holy Trinity and the entrance tower, which were part of the fort, and other parts can be discerned only in traces of the foundations. The name of the fort itself is Sokolac, a name that spread among the people after the Frankopans left the area. The fort has historically had different functions: during the Frankopan and during the Military Frontier (defense against the Turks) and therefore two historical layers can be seen. The Frankopan layer can be divided into several units, the palace, the chapel of St. Trinity and a square entrance tower. All these buildings were interconnected, organized around a spacious courtyard in the center.