Baba Vida Fortress is considered to be the most representative historical monument in the entire region, due to the fact that it is a fortified medieval fortress that has been preserved almost entirely. The first historical data show that on this location there was at the beginning a Roman fortification with the name of Bononia, built for observation. The fortress was then enlarged during the Byzantine and medieval periods, due to the strategic position that allowed the control of the traffic on the Danube, the surveillance of the commercial roads, but also the military defense of the city. The oldest existing walls date from the tenth century, from the period of the Bulgarian Empire. Baba Vida Fortress was the residence of Tsar Ivan Stratimir, the founder of the last Bulgarian dynasty. The castle has two surrounding walls, an inner courtyard and two outer courtyards. The interior walls have a height of over 2 meters, being supported by 9 defense and observation towers, the entire surface occupied by the fortress covering about 9,500 square meters. During its time under Bulgarian rule, the fortress was permanently enlarged and strengthened, many of the constructions and fortifications since then being kept intact to this day. In 1689, under the rule of the Turks, the fortress was modified for the use of artillery, being also used as a weapon and military storage facility, but also as a prison. After the liberation of Bulgaria in 1878, the castle became the seat of military authority, being opened to the public only in 1927, and in 1964 it was declared a historical monument of national importance, entering the compulsory circuit of each tourist. The fortress is sometimes used as a setting for movies, theater, concerts or various artistic representations.