Amid the great northern war, the 19-year-old Carl Gustaf Tessin (1695-1770) travelled through Europe to Paris, where he was to study for two years (1714-1716). His father, Nicodemus Tessin the Younger, hoped he would succeed him as the surintendant des bâtiments. However, the son had no aptitude for an architectural career. Instead, he became a passionate art connoisseur and collector. Tessin's notable meetings with, among others, prominent artists of the early Rococo period, such as Claude Gillot and Antoine Watteau, are famous. He documented his impressions of French art and architecture in his diary, published here for the first time.