 Słupsk developed from a few medieval settlements located on the banks of the Słupia River, at the unique ford along the trade route connecting the territories of modern Pomeranian and West Pomeranian Voivodeships.This factor led to the construction of a grod, a West Slavic or Lechitic fortified settlement, on an islet in the middle of the river.Surrounded by swamps and mires, the fortress had perfect defence conditions.