In 1332, the Florentines planned to build a bridge here called the Ponte Reale in honour of Robert of Anjou, and started with this tower to defend its entrance on the right bank. A massive flood the following year put paid to the idea, and instead the Florentines built a pescaia or weir, still in place, to defend the city from upstream attacks, control fishing and assure sufficient water to run the local mills that powered the city's dye works and mint (zecca) that produced all those florins. It also offered a 'secret' emergency wading passage over the river.
Today it stands proud and lonely surrounded by Giuseppe Poggi's 19th-century circle of boulevards, the viali di Circonvallazione.
Images by: Giovanni dal Orto, Creative Commons License