Słupsk (Polish: [swupsk] ; Kashubian: Stôłpsk [stɞwpsk]; German: Stolp [ʃtɔlp]) is a city with powiat rights located on the Słupia River in the Pomeranian Voivodeship in northern Poland, in the historical region of Pomerania or more specifically in its part known in contemporary Poland as Central Pomerania (Pomorze Środkowe) within the wider West Pomerania (Pomorze Zachodnie). According to Statistics Poland, it has a population of 88,835 inhabitants while occupying 43.15 square kilometres (16.66 sq mi), thus being one of the most densely populated cities in the country as of December 2021. In addition, the city is the administrative seat of Słupsk County and the rural Gmina Słupsk, despite belonging to neither.
Słupsk had its origins as a Pomeranian settlement in the early Middle Ages. In 1265, it was given city rights. By the 14th century, the city had become a centre of local administration and trade and a Hanseatic League associate. Between 1368 and 1478, it was a residence of the Dukes of Słupsk, until 1474 vassals of the Kingdom of Poland. According to the peace treaty of 1648, Słupsk became part of Brandenburg-Prussia. In 1815, it was incorporated into the newly formed Prussian Province of Pomerania. After World War II, the city again became part of Poland, and from 1975 to 1998 it was the capital of Słupsk Voivodeship. It is a railway junction located on the main railroad between the Tricity and Szczecin. The local Renaissance Ducal Castle houses the Museum of Central Pomerania with the largest collection of paintings by popular early-20th-century artist Stanisław Ignacy Witkiewicz.