ITAMore information :
When the Pisans, between 1250 and 1260, extended their city walls to encircle the area known as Colle del Paradiso, now Piazza San Francesco, they also created the opening then known as Porta del Mercato or Porta Santa Maria.
This access point consists of a double gate: past the outer gate, a large ashlar sandstone portal described in historical records as the "external gate of Santa Maria," there's an inner opening with three arches topped by a rather worn image of Saint Michael, the city's patron saint. On the wall of the gate facing Corso Italia, under a gabled roof, there's a mid-19th-century fresco depicting the Immaculate Conception.
In this area, as outside Porta Sant’ Angelo, there was also an enclosure (a "serraglio") to compel travelers to pay customs duties, and "caselle" (small shelters) for guards and toll collectors. To defend the northern section of the city walls, there were several towers, one of which, the Torre degli Assi, is currently occupied by a bar. This structure was so named because it was surrounded by scaffolding built with large wooden planks, of which today only the large stone corbels that supported them remain.
The tower, originally more imposing than it appears today, was lowered in the 18th century and covered with a single-pitched roof. Interventions from this period also included the demolition of the adjacent city walls, aimed at recovering building materials and creating overlooks and terraces facing the valley "to have light and see the view."
