Olsztyn

Olsztyn stands on the Łyna in Warmia, where a watchtower and a cleared forest site preceded the medieval town. The Warmian cathedral chapter granted it municipal rights in 1353, and its brick castle became the chapter's fortified administrative seat. German and Polish settlers knew the place by the related names Allenstein and Olsztyn.

Nicolaus Copernicus lived in the castle while administering the chapter's estates. During the Polish–Teutonic War he organised the defence of Olsztyn, which resisted the Order's attack in 1521. An astronomical table he made on a castle wall recalls his scientific work alongside his demanding practical administrative duties there. The town remained part of Warmia under the Polish Crown until the First Partition in 1772 placed it under Prussian rule.