The article examines the historiography of the founding of Turku, the oldest town in Finland. The early phases of urbanization and the year of founding have a widely discussed background, which derives from early modern historical writings. A recent discovery of a 17th century document from Hague which mentions the foundation on the town in 1310 is compared to a thorough analysis of the 16th and 17th century chronicles and other writing of history. Our key conclusion is that the early modern historical texts share a common understanding that the town was founded around the year 1300, possibly based on a local tradition. There are also some evidence that the town could have been founded in 1310 as the 17th century document mentions. These dates concur with the prevailing archaeological view on the begin of urban settlement in Turku.