Here we present historical facts, important persons and key-locations that led to the development of the Bacillus Calmette and Guérin (BCG) vaccine at the turn of the 20th century to fight against tuberculosis. For that, we have browsed historical publications and gathered original data concerning i) co-inventors, Albert Calmette and Camille Guérin, and ii) the location here it all began, the Pasteur Institute of Lille, France. This historical overview lights up the importance of the co-inventors’ respective personalities and of the local political willingness to pull together scientific efforts to relieve the northern region of France from contagious illnesses. As a result of their continuous efforts, BCG vaccine is named after its co-inventors. It is strongly justified since Calmette and Guérin have remarkably put together their expertise, courage and eagerness to develop this outstanding preventive medicine. This review emphasizes Calmette and Guerin's contributions to inventing the BCG vaccine and their enduring legacy.