The historical stroll through the old town of Geneva which is described in this article was conceived to recall the importance of the street in issues relating to health before modern medicine. The street was then ambiguous, both itself a sanitary hazard and a source of medical assistance. This article discusses three key aspects of medicine in the street at this period: (a) the practices of charlatans, both operators and medicine peddlers, active in the city squares and streets; (b) first aid given to those who suffered from accidents in the streets and, finally (c) an important episode in the genesis of public health, the question of inoculation against small pox and the danger in which the general public was placed when confronted to recently inoculated individuals in the streets and public promenades.