It is the administrative centre of Chavdar Municipality, which lies in the easternmost part of Sofia Province.
Septemvri starts the 1948/49 season in the newly formed A Republican Football Group, but only six months later is separated from Chavdar and removed from the division, with the current title given to CDNV, Chavdar's new name, which would ultimately become CSKA Sofia.
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In May 1948, the club, then playing in the 1st Sofia Division, is briefly merged with second-division Chavdar (Sofia) and the unified club wins the 1948 Bulgarian Championship by overcoming Levski Sofia at the final.