The real beginning of the fortification and building of Bar started during the middle Byzantine period, when it became the border fort for the Durres area in the 8th or at the beginning of the 9th century.
Since the town was then the seat of the archbishopric, the design of its fortification had to be strong and stable, and it consisted of semicirculat towers which defended the town gate. These are the oldest preserved architectural remains in the town.
The fort was placed in the triangle between the town's citadel, the gate ("Postrella) and the lower gate, and it consisted of vertical walls which ended in spikes. The role of the spikes was to protect the defenders from arrows or rocks which the attackers might throw. In order for the defenders to come and stand behind the spikes in the walls there were wooden planks in front of the town walls and there was most certainly a ditch filled with water, which is visible in the engravings from the later periods. The walls on the eastern side were lower and less carefully built, unlike the walls turned towards the noth-west, the direction of the most dangerous possible threats.
The position of the town entrance was significantly different from the 9th to the 13th century with regard to its position today, which started to develop in the late 13th and 14th centuries.
The town could be reached by stairs carved out of the rock, which passed by St. Illarions Church; then the road passed the graveyard with the church, in front of the entrance to the town. This graveyard was discovered thanks to the latest archeological research.
The strategic, economic, political, religious and cultural influence in the 11th century must have driven the expansion of the town walls, but, basically, we know very little about this. The design of the fortified Bar during the time of the Duklja kingdom relies on the Byzantine defence system, but it is necessary to assume that its significance as the regional centre and the archiepiscopal seat were enough to ensure the building of stronger fortifications and the reinforcement of the old ones.
Research has proven that during this time there was no citadel as in the later period, but that a large circular tower dominated this area at the corner of the "Acropolis", today's citadel. Most probably, this tower collapsed when the defensive system was altered in the 14th century.
The southern part of the town was significantly different in those days. Research has revealed a graveyard from the 11th century, which had to be outside the walls, because of fear of infection. Judging from the recovered remains of the charred wood buildings, certain parts of the town were made from post-and petrail construction (timber and plaster), as well as the houses inside the walls.
The material rise of the coastal towns in the 14th century was a strong incentive for this architecture.
It was especially felt after the stabilisaion of the political and social circumstances in the late 13th and especially in the 14th century, when the feudal class began to strengthen suddenly and when the nobility was distinguished as the most powerful class in town.
Bar started to spread and to assume a new role. This was especially obvios during the time of Helen Anjou, wife of Uros I Nemanjic. That is when the main gate received the new rich "look" with the church above the passage, which provided an atmosphere of solemnity for the entrance of the archbishop and the ruler.
In the 13th and 14th centuries the inner walls were reinforced in the area of the defensive objects. In this part of the wall today there are the remains of a rectangular tower. In addition, the town was enlarged in the first half of the 14th century with a "new" outer wall, and the lower town was also built, which significantly extended the area of the fortified town.
The lower town started to be fortified using brick walls in the 14th century at the latest, and its vast walls suffered many repairs and additions during their existence. These walls originally ended in spikes, but later, during the Venetian and Ottoman rule, loop-holes were added. From the lower part of the town there was a passage through the Lower Town gate which led to the river and the eastern and south-eastern side of the town.This passage enabled communication with feudal lands in the plains. Similar to the upper gates, a chapel was built in this tower-gate over the passage, which had a ceremonious role.
Research done in 2004 definitively proved that the upper castle - in the original citadel was built in the late 13th century.The digging within this building revealed that there was a Romanesque churche whose remains are visible today.
In the middle of the 15th century the tower was added to the wall and helped extend the town during the first half of the 14th century. In this place there was originally a semi-circular gate. The tower was adapted for defense with guns. It had openings for muskets and cannons and ended in battlements. There was also a tower in the westernmost corner of the town, and then in the area between the citadel and Londza.
In the middle of the 15th century another inner gate was built. Only a great arched portal remains today as well as the openings for cannons which were later added.
The use of gunpowder and more powerful cannons in the 15th and especially the 16th century caused the change in the defensive architecture of the town whose appearence was significantly changed by them. Lower and wider, but more massive towers, most often with a round foundation, and lower and thicker walls which were also reinforced from the inside, replaced older constructions or were directly built in front of them and on top of them.