The town 's notable sites include : During World War II , Kórnik ( renamed '' Burgstadt '' ) was annexed by Nazi Germany from 1939 to 1945 as part of '' Landkreis Schrimm '' , Reichsgau Wartheland . On 20 October 1939 a mass execution of 15 local residents was carried out as part of Operation Tannenberg
Operation Tannenberg
Operation Tannenberg
Kórnik