The southern wall is interesting because it has preserved the old loopholes, which were intended for shooting with bows, crossbows, and later with light firearms.
At the same height, they had different widths and spaced 3.3 m apart. Three of their types alternated on the wall. The gallery floor was supported by wooden beams with a cross section of 20X20 cm.
In the time of Gediminas, two rivers merged into a single channel behind the southern wall of the Castle: the Lideya (flowed behind the eastern wall) and the Kamenka (flowed behind the western wall). Nowadays, behind the southern wall of the Castle, you can see a picturesque lake shaped like a heart. It was created relatively recently, in 2010. The surface of the lake is 1.1 hectares, the depth is only 1 meter 30 centimeters.