The area of the current square corresponds to the area where the most ancient nucleus of the city was developed, the Cornio place, already documented in the ninth century and probably founded by the Lombards, where there was a small village and the pieve dedicated to Santo Stefano.
Ample and articulated, it was developed because of the baptismal pieve, then become a Cathedral.
Since the fourteenth century the square was a place for carnivals, markets, outdoor games and above all the monstrance of the Sacred Belt that attracted, as it does now, crowds of worshippers devoted to the Marian relic.
The square is framed by buildings that are mostly from the fourteen century. The southern side is faced by the nineteenth century Palazzo Vestri (current headquarters of the Travel Agency and Tourist Information Office) in front of which there is a statue of Giuseppe Mazzoni - Prato's politician - made by Alessandro Lazzerini, on the side of the Duomo the Bishop's Palace and in front of it, Palazzo Dragoni renovated in the Nineteenth century. At the centre of the square the nineteenth century fountain of Pescatorello called "Fontana del Papero" (1863) sculptured by Emanuele Caroni and Ulisse Cambi.