The part of the wall which is located furthest west and which came to form Wisborg Castle's southern defensive wall is called The Castle Wall. When the construction of the castle began in the 15th century, the Visby City Wall already existed and was utilized by building the castle together with the wall. The Sail Tower (Segeltornet in Swedish), was originally a corner tower in the wall between the southern wall and the seaside wall. The remaining foundations of the tower show that it was stronger than the other towers along the southern part of the wall. It did not have openings facing the town. A flanking wall went from the tower down the slope to the sea, prohibiting passage on the outside of the part of the wall facing the sea. Next to the remains of the Sail Tower, parts of that wall and a gate in the earliest wall remain. This gate also served as a passage between the inner courtyard of the Wisborg Castle and the outer defensive structures.

The castle and parts of the Castle Wall were destroyed in 1679 by the Danes before they finally left Gotland completely. The castle wall on a stretch from The Sea-maiden Sconce and to the west has been rebuilt on various occasions so that there is uncertainty about what is original. 

Photo: W.carter