At the end of the XIV- beginning of the XV century the grandson of Gediminas, Vytautas (Vitovt) the Great Duke, rebuilt the Castle and made it one of the most powerful in the Grand Duchy of Lithuania. To strengthen the construction, the northeastern tower is being built, with the expectation for conducting cannon fire.
In plan view it was a gotten out of shape scalene quadrangle, close to a square with sides of about 12 m. The thickness of the northern and eastern walls of the tower, attached end-to-end to the two-meter walls of the Castle without bond, reaches 80 cm, and the thickness of the separate southern and western walls is equal to 3 m.
The finds of archaeologists indicate that the tower also served as a housing.
It is considered that on its upper floors there were luxurious chambers and halls, and on the lower floors there was a court, an archive and a prison.
The northeastern tower has remained to a height of 4 to 8 m or more. In 1980, the tower was completely restored.
In 2017, it is opened an exhibition in the tower “The Lida Castle. Historical events and figures”.