The Slit Bottle (Sprundflaskan in Swedish) tower was erected around the end of the 14th century with the dual purpose of strengthening the town defenses and reinforcing a weak spot in the wall. Its present name has been used since the 17th century and possibly stems from the tower shape which originally resembled a bottle.
Next stop - The Fallen Wall https://reveal.world/story/the-fallen-wall
Photo: Dmitry G