In the city, until the thirteenth century, there were three places where trade was carried on, among them the market of San Giovanni Battista in Trebbo Beccadelli, later called Santo Stefano.In 1303 Trebbo Beccadelli, as Guidicini tells us, was enlarged, demolishing various blocks of flats, and paved with cobblestone. This intervention was carried out thanks to the contribution of private citizens who lived in the area. Guidicini also tells that a large oak tree, surrounded by seats used by local notables to meet and stand in the shade, persisted in the middle of the renovated square. About 1335, the oak was taken down as an affront to the Beccadelli family during a popular revolt.
Over the following centuries and up to the present day, the square has undergone various transformations, in particular due to the sloping terrain, which converges towards the main entrance to the Basilica, located at the square’s lowest point. Height modifications, the creation of continuous overhangs or inclined planes has had a decisive influence on the relationship between buildings and open spaces; the manifold solutions that have been chosen over time have also changed the role of the portico, which is the fulcrum of that relationship.Historical iconography documents different solutions aimed at protecting the entrance of the Basilica, until the intervention carried out in 1934, probably due to the restoration of the sacred building. A gap had been created between the main floor of the square and the churchyard itself, connected by a 7-step staircase. To protect the overhang, of considerable height, an iron balustrade was installed, supported by pillars with an octagonal base in stone.In 1991 the project of Luigi Caccia Dominioni was inaugurated, which realizes a large continuous basin without any drop in height; the staircase and the balustrade were therefore eliminated and the cobblestone pavement was rebuilt.