Many explanations have been given and continue to be given: 1) The shell is the symbol of pilgrims, who had the right to wear it on their cloak after visiting the tomb of St. James in Santiago de Compostela. As Siena is a hospitable city for many pilgrims, the shell shape seems appropriate. 2) The shape recalls the mantle of the Virgin, stretched out to protect Siena and the Sienese. In fact, the city is historically devoted to the Virgin Mary. 3) But the real reason for this shape is certainly due to the configuration of the land, which descends downstream and was natu-rally suitable for hosting this particular shape.

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