Despite a certain confidence born of his many gifts, the newly arrived, adolescent Leonardo must have found the urban congestion of Florence and the desperate squalor of so many who lived there a bit intimidating. From the airy public squares spanned countless, winding streets and blind passages, many made almost impassible by vendors’ stalls and filthy shacks. As in most European cities, the poor, rural émigrés, and itinerant workers – altogether, roughly half of Florence's population – mainly hunkered down in makeshift housing, crude wooden structures and lean-tos, braced against churches and other masonry buildings.

Agricultural life was then much more intrusive and obtrusive than it is today. Horses, donkeys, cattle, and other livestock were everywhere led through the narrow streets. Piles of hay and manure were ubiquitous. Carts and mule trains, loaded with wool, raw silk, leather, and produce, angled their way past these obstacles and large open-pit quarries of pietra forte, the stone from which most of the palaces and houses were built. Animal parts that could not be used by butchers or leather makers were freely discarded in the streets, usually at the spot where the livestock had been slaughtered. Carcasses floated in the Arno as well, along with massive debris and chemical residues generated by the wool workers and dyers, who labored under lofty wooden sheds (tiratoi) and pavilions along the river.