Zağnos Bastion was built of hewn stone with a quadrangular plan in time of Alexios the 2nd. It was used as a dungeon for a while.

It differs architecturally from the other archedbridges in the Eastern Black Sea Region. The most important differences are its stone columns set on rocky surface, wooden body and tiled roof which give its originality. In old times, the buildings were substantially wooden. Hapsiyaş Bridge which is one of the most favourable works of art in the city, is also built that way.