 At that time, Lidzbark city had one of the largest populations in Warmia, similar to Braniewo.In Lidzbark, Sikorski researched historic documents pertaining to the history of Poland's Baltic seashore (Pomerania, Warmia, Mazury, Prussia), and its extant architectural relics, documents, and other materials relating to Nicolaus Copernicus.Following the death of bishop Watzenrode in Toruń on March 29, 1512, Copernicus only sporadically visited Lidzbark, either as an emissary of the Warmia Chapter, or as a personal medical doctor for the successive bishops