Learning about Polish astronomer Copernicus.

Copernicus lived at the Castle of Warmian Bishops in Olsztyn, where he would spend the most dramatic days of his life. The castle in Olsztyn was under the jurisdiction of the Kingdom of Poland from the mid-15h century and was administered by Catholic Church officials of the Warmian Chapter. One of them was Nicolaus Copernicus, who in 1516-1521 administered the chapter’s property, including its nearby lands and the castle in Olsztyn. 
During his stay at the Olsztyn Castle, Copernicus also conducted astronomical observations. He was particularly interested in planets and issues related to vernal and autumnal equinox. In order to follow the equinox better, he constructed a special astronomical table. Today the table is installed near the entrance to a castle chamber, which Copernicus once occupied and which houses an exhibition dedicated to the astronomer. 
http://poland.pl/tourism/urban-tourism/copernicus-olsztyn/