15km/9mi southeast of Norrköping can be seen Söderköping (pop. 13,000), founded in the 13th century as a trading station for Lübeck merchants who built a large church here (as they did at Skänninge). The church (St Lawrence's) was completed 200 years later, at the end of the 15th century. The town's location at the eastern end of Gota Canal brings many foregin tourists by boat. Excavations in Storgatan, Vintervadsgatan and elsewhere in the town have brought to light merchants' and craftsmen's houses and equipment which show that for a time during the Middle Ages Söderköping was one of Sweden's principal trading towns.
In 1567 the town was partly destroyed by Danish troops, but was rebuilt in stone. King John III made Norrköping the administrative center of the region and promoted the development of mining; and thereafter Söderköping's trade declined, and the German merchants left the town. Its inhabitants then turned to fishing in the skerries for their subsistence. A trading settlement which was now established on the islands of Björkeskär and Viskär held a monopoly of the fisheries off the coasts of Östergötland until 1731. Later the mineral water of St Ragnhild's Spring acquired some reputation and was marketed commercially.
Among features of interest in the town are the Drothem quarter with its church and a number of old buildings around St Lawrence's Church, including the belfry (1582) and the schoolhouse. On Gilleskullen is an open-air museum with old houses from the surrounding area. There are fine views from the Ramunderberg with its castle.