Schron bojowy dla km. Regelbau C-1 is a German splinter-proof shelter located in Kętrzyn, Poland. Built in 1942 during World War II, this bunker was constructed when Kętrzyn was still known as Rastenburg and part of German territory. The structure served as an air raid shelter, designed to protect personnel from bombing raids that were expected or had already begun in the region.
As part of the German defensive infrastructure in occupied Poland, this Regelbau C-1 type bunker represents the standardized military construction methods used by Nazi Germany during the war.