This article deals with the image of the Swedish architect Nicodemus Tessin the Younger (1654-1728), one of the main characters in the history of Swedish architecture. The image of Tessin was established by Swedish art historians at the beginning of the Twentieth century, partly as a parallel to other architects of a national reputation, notably Christopher Wren and Karl Friedrich Schinkel. The article concentrates on the image established by the Swedish art historian Ragnar Josephson in creating his monumental monograph Tessin, published in two volumes 1930-31. However, alternative images of Tessin, established by Josephson's contemporary colleagues, are used as comparative references. The article also offers a brief outline of the earlier periods of research on Tessin, and eventually emphasizes the importance of further research in the field of architectural historiography.