The Girone

Before the Arno reaches Florence it forms a wide bend to the left before resuming its course towards Florence and for this reason this area is called the Girone (the big bend). It's the location of a small village in the municipality of Fiesole.
Leonardo stated that in proximity to the Girone there was a rock barrier which created another lake situated above that of the plain between Florence and Pistoia, bordered by the barrier at La Gonfolina.
Indeed beside the lake in the Florentine plain there was a second one.......”in the upper Valdarno or towards Arezzo […], which in the aforesaid lake [the Arno] deposited its waters, contained where today you see Girone, and it occupied the whole of the said upper Val d'Arno covering an area 40 miles long...” (Codex Leicester c. 9r).