Complex sentence: Towards the northern part on the left side there used to be a building of the governor of arms, and today it is the old city hall, left to it were the barracks which became the gallery of the museum of Knin.
Split into simpler sentences: Towards the northern part, on the left side, a building of the governor of arms used to be there; today it is the old city hall. Left to it were the barracks which eventually became the gallery of the museum of Knin.