Baba Vida fortress in the town of Vidin on the river Danube in Northwesternmost Bulgaria is the only medieval fortress that has survived to this day in this country.
A portulan, a travel guide of sorts, from the Roman times first mentioned the fortress under the name Ad Malum (probably of Celtic origin). The Romans later changed the name to Bononia, which the Slavs pronounced as Budin, and the Proto Bulgarians as Bdin. The present-day name Vidin appeared for the first time in Ottoman registers as early as the XV century.
Baba Vida is a medieval fortress built on the foundation of the Roman Bononia fortification that existed for five centuries till the mid sixth century A.D. It was part of the Danubian frontier of the Roman Empire. The citadel had two parts, a housing and economic part, and a defensive part. The castle represented a square building encircled by two walls, an inner wall and an outer wall, forming a courtyard in between. The castle towers were built on the inner wall. Four of them occupied the four corners pointing to the four directions north, south, east, west. There were also five lateral towers, and of course the main entrance tower, built on the outer wall. The fosse in front of the castle was filled with water from the river Danube. It had a wooden bridge that went up and down. The principal construction works date from the period of the Second Bulgarian kingdom, the late XII –early XIV century. During that time Hungarian and Bulgarian rulers took turns to hold the possession of the fortress. The last dynasty of Bulgarian kings before the country fell under Ottoman domination, the Shishman dynasty, originated from there. The building technique combined stone and brick bound by mortar. After the fall to Ottoman domination the castle was turned into a fortification and served that purpose right till the early XIX century. Baba Vida fortress underwent rebuilding to allow for fire from small-calibre rifles and canons from the outer wall.
The inner courtyard was home to the guards and also housed the many warehouses. There used to be a chapel in the XIII-XIV century unearthed during excavations and researchers assume that the fortress was also home to the feudal lord of the region. In the XVII-XVIII century the Ottomans built stone quarters for the garrison.