C-byrån was a Swedish secret intelligence agency established in 1939 under the Swedish Armed Forces. It was headed by Major Carl Petersén. During World War II, C-byrån organized intelligence operation
Plaque on Sibyllegatan 49 in Stockholm: "C-byrån operated in this building 1942-1945. The Swedish Armed Forces honor the women and men in the intelligence service who here, in silence, made great efforts for Sweden."