The hillfort stands in the valley of a small nameless stream. The slopes of the hillfort are steep, reaching a height of 13 m, and to the south of the hillfort, it is surrounded by an embankment. Its outer slope reaches 6 m, and 4 m from the platform. The platform itself is oval in shape, 40 m long in an east-west direction and 30 m wide. There are traces of a rampart on its northern edge. It is believed that the Vembūtų hillfort was the site of the town of Vykinto, the capital of the Samogitian dukes. The Vykinto castle in Tvirement mentioned in the chronicle of Ipatijus is the only castle in Samogitia known to all Russian chronicles of this period. The chronicle suggests that this was the center of the region, with strong fortifications and capable of harboring many defenders. In 1251, when Mindaugas fought against his rebellious vassals, not only Samogitians but also Polovtsians and troops of the Russian prince Danilo were stationed in this "town of Vykinto." The entire Vembūtų castle complex extends more than a kilometer to the east. This shows that Vembūtai Castle was one of the largest defensive structures in Samogitia. These fortifications could have been used to gather large military forces. In this respect, the castle surpasses the nearby castles of Medvėgalis, Burbiškiai, and Plinija.