The castle was built on plain ground and was designed for flank defence. The rectangular castle's yard covered approximately 1.8 hectares and was protected by walls 15 metres high and 2 metres thick. The castle had 4 gates and towers. The main tower (donjon), about 30 metres high, was used for residential quarters. Medininkai was first mentioned in 1392. The castle was badly damaged by a major fire in the late 15th century. Because of increased use of firearms, this type of castle was no longer suited for defensive purposes and was later used as a residence. During the 17th – 18th centuries it was reorganized into a farm and a bakery.