In the context of this artwork, explain the Defensive structures of the Medieval Stockholm.
Along the western shoreline are several defensive structures of various ages. The wooden defence structure built along the shore around 1650 is absent in the painting, but the double row of piles protecting the western harbour is present.  It served both as a defensive structure and, because a duty was imposed on all incoming ships, as an important source of income for the city. The western defence structures were neglected around 1500, which resulted in settlements being constructed between the western city wall and a shoreline constantly pushed westward by landfill, just as the painting renders it.While the old city wall is not discernible in the painting, several of the towers sitting on the city gates are (left to right):
The tower with a cone-shaped roof just to the right of the Greyfriars monastery was called Draktornet ("Dragon's Tower"), and in 1535 served as a prison.
Just to the right of it was Gråmunketornet ("Greyfriars Tower") with stepped gables and a large gate leading to Riddarholmen island. Excavations in the 1950 showed that the gate was 1.5 metres (5 feet) wide.
The second tower with stepped gables but without a gate was the Lejontornet ("Lion's Tower"), the foundations of which were rediscovered during an archaeological excavation in 1984 and are now part of the interior of a restaurant on Yxsmedsgränd.
Between Lejontornet and the southern city gate flanked by two boats is a wooden structure, roughly triangular in plan; this is a defensive tower called Kivenäbben, built in 1520–1523 on piles in the water.Lastly, next to the southern city gate is an open space, believed to be the precursor of present-day Kornhamnstorg, the square where ships from the Lake Mälaren region used to deliver corn and iron.
painting Yxsmedsgränd Mälaren Riddarholmen Greyfriar Lake Mälaren right Kornhamnstorg left