Copernicus spent most of his adult life in Warmia (Ermland), a dominium of the Bishop of Warmia and of the cathedral chapter, covering an area of 4250 km2 and occupying around one-third of the total area of the Diocese of Warmia (as marked out by the papal legate William of Modena in 1243).

His long-term sojourn in, and very strong loyalty to, Lidzbark Warmiński (Heilsberg) in 1503-9 was a formative period in the life of Copernicus in terms both of his personal and scholarly development. In the mid-14th c. the strongly-fortified gothic castle had become the see of the Bishops of Warmia and the administrative centre of their dominium.

Established in 1260 for the purpose of common divine worship and to help the bishop manage the diocese, the chapter of Frombork (Frauenburg) was the type of corporation that enjoyed a good deal of autonomy, not only in the ways it organized its church activities or its internal affairs, but also in the way it selected its members and enacted its statutes. These were drafted and passed in cooperation with the bishop.

Towards the end of 1510 Copernicus came to reside on the cathedral hill dominating Frombork (Frauenburg), a town with a population slightly above 1,000 with a magnificent cathedral dedicated to the Assumption of the Virgin Mary and St Andrew the Apostle which, together with other buildings located in a square nearby (chapterhouse, school, canonical lodgings and a library), was then an important religious and cultural centre.

Upon assuming the office of Administrator General (8 November 1516) Copernicus took up residence in Olsztyn Castle (Allenstein) then regarded as the best-protected stronghold in Warmia (one of the reasons the chapter’s archives had been moved there in 1502). 

Little is known about the private life of Nicolaus Copernicus until he reached an age sufficiently mature for it to be difficult to suspect him of promiscuity. Before the year 1538, a mysterious woman appeared in his life who was the source of several interventions by Bishop Dantyszek (Dantiscus). He rebuked the old astronomer and requested the dismissal of the "housekeeper" from his see. Her name was Anna Schilling.

Upon the arrival in Warmia in 1538 of the newly-elected Bishop Johannes Dantiscus (Johann von Hoefen), Nicolaus Copernicus’ life changed for the worse. Accused by the bishop of cohabiting with his housekeeper Anna Schilling the astronomer had no choice but to dismiss her.

Copernicus’ library constitutes a very important testimony to his education and interests, but unfortunately, most of the books he owned have been either dispersed or destroyed.