When the Venetians arrived in the town, there was a need to reinforce and secure the north-western slope even more. The reason for this  was the great strategic importance of the town as one of the closest fortifications to the advancing Ottomans. in the State Archive in Venice there are many documents which relate to the approval of money for the building of fortifications. The oldest document mentions 1498, when ist was decided that that all the income from Bar should remain in the municipality so that the money could be used to build forts (and probably reinforce the old ones). At the beginning of its more secure rule during the middle of the 15th century, the Venetians instantly tried to reinforce, mend or build new defensive structures.
However, almoust fifty years later, in 1546, a sum of 100 ducats is mentioned for the building of the walls, which leads us to the conclude that the Ottomans attacked the town which was not fortified well during the most of the 15th century. Today it is obvious from its strikingly designed system of bulwarks, ravelins and walls that the Venetians managed to complete the fortifications. Therefore it is surprising that the Venetians handed over the town without a fight.
The massive Venetian wall, with bulwarks started to be constructed in the beginning of the 16th century. Strong askew walls and the powerful bulwarks reinforcced in the bottom part are characteristic of the new concept of defense from increasingly powerful firearms. The entire western and northern part of the walls with bullwarks and the ravelin is the most monumental building in the city today.
Todays entrance gate and the bulwark have been added to the older town tower, which partially preserved the traffic netwerk, and apart from the large door, coated with iron, there was also a door in the entrance to the town on the west. Above the gate from the inside, a Venetian lion was carved during the rule of Prince Bernardo Canali.
St. Illarions Church, which is a part of the Gavodola (or "Gavansola") tower, served as the central room from which corridors led to three smaller rooms where cannons were placed. The round tower with a bulwark makes a single construction, but it was not erected to the same time. The tower was built first during Venetian rule together with the town walls. Later, most probably near the end of Venetian rule, or during the Ottoman times, the bulwark was added. Inside it there are several larger and smaller rooms. Gavadola is mentioned in 1553 and 1555, when it was recommended that the tower's wall should be reinforced.
Tatarovica Citadel, as it can be seen now, is a military defensive system, which was largely created in the beginning of the 15th century in the place of a smaller rectangular fort from the end of the 13th century. This protruding town citadel was situated in the north-eastern end of the tallest slope of the rocky area, at an altitude of 150 meters.
it served as the defence for the northern corner of the town, but it also functioned as the military garnison with prisons, houses  for the attendants and a cistern. Most of it was built immediately, as a great construction undertaking. This way, the northern side of the town was reinforced even better. The most important point of the citadel was its bulwark with a great platform at the top, where several cannons could be placed.
It was reconstructed during the Ottoman period, and from the north-east end, a gunpowder-magazine room was added, along with the room for storage of ammunition.
the ravelin was erected along to house large cannons. it enters the bulwark wall with its northern wall, and in the west it was reinforced and there are two large openings for cannons in it. A Staircase, probably built during the late Middle Ages used to lead to the ravelin. There was also a corridor which led to the ravelin, and which penetrated the western wall of the building 164.
In the southern part of the main gate there is a dark room in the south-western sloping wall, called Selimbegovica or "Selim-beg's prison". According to a long recorded tradition, Selim-beg used to hide here, because the strong walls provided safety from the mortar strikes from the Montenegrin cannons in 1877 - 1878.