Medieval castle "Baba Vida" was built on the foundations of the ancient fortress "Bononia". Baba Vida is located on the big curve of the Danube River at Vidin. It is assumed that at the end of the tenth century castle has been built and used for building stone of the ruined Roman fortress "Bononia" and "Ratsiaria". It is heavily fortified and expanded during the reign of king Ivan Sratsimir. Many of the buildings constructed at the time, remained indestructible. In the Middle Ages the Fortress had 10 towers – 4 angle and 5 side associated with inner wall, the thickness of which is about 2.2 m, and the outer wall is built one entry tower that guarded the drawbridge. The height of the inner towers was 16 m. The moat around the castle with a depth of 4 m and its width is about 6 m.