It was a fortress with three towers, the largest one on the east and two smaller ones on the west side, mutually connected with walls 1.80 - 2 m thick. It was built hastily with small stones, obviously there was no time and funds for sculpting the stone blocks. Inside there was a narrow yard with cisterns for collecting water. Fortica served for permanent accommodation of soldiers, as a warehouse for ammunition and gunpowder and for storage of food, with kitchens and dormitories.
Archaeological research discovered the walls of each tower as well as the connection walls. The threshold of the entrance door was also found. The entrance into Fortica was on the south side facing Otočac. The entrance door was high above the ground so during construction the only way to get into Fortica was with ladders, and a porch with stairs was built later on. The hill Fortica was just a bare hill without trees during the military usage. This was caused by defense reasons. The first commander of Fortica was Andrija Kolaković. Fortica was abandoned in the second half of the 19th century when Otočac commenced its development as an urban centre. All important military buildings of Otočac regiment were located below Fortica. The fortress started to lose its significance in early 19th century, which is well illustrated by the fact that it was converted into gunpowder storage facility in 1804. In 1882 strong wind lifted up and threw on the floor the roof of the widest tower, so apart from the negligence, the weather made its contribution to deterioration of Fortica.
In the early 20th century Fortica was afforested. Pharmacist Častek had pines planted on private property on the hill. The new forest developed nicely until the WW II. In 1941 Italians who came to Otočac had the trees cut and placed their artillery battery there. It is interesting to mention that Fortica, in its restored and preserved condition, is now the only remain of renaissance in Otočac area. Namely, before the renaissance it was customary to build rectangular rather than triangular towers, and in renaissance the fortresses and castles were reinforced with round towers. Fortica is a true rarity, because it is one of only two remaining triangular towers in Croatia, and in Europe there are only several of them.