Stoup, or holy water basin, in inlaid marble, sculpted by Jacopo di Piero Guidi in 1380. The basin and angel with amphora are replicas made in 1790; the originals are now in the Cathedral museum.

This monumental work, finely crafted and remarkable for the complexity and richness of the decoration, is attributed to the sculptor Jacopo di Piero Guidi. It has the appearance of a model structure inspired by Giotto's bell tower, in the forms, use of materials and decorations, as well as in religious and civil meanings.

The upper frame bears the words of Psalm 51, verse 9, referring to the holy water collected in the basin: ASPERGE ME DOMINE ISOPO ET MUNDABOR LAVABIS ME ET SUPER NIVE DEALBOR, or "Sprinkle me with branches of hyssop and I will be pure; wash me and I will be whiter than snow". The statue at the summit also refers to spiritual purification, with an angel of heaven pouring blessed water from a jug (although the original of this sculpture was created in the 15h century, meaning later than the basin and substructure).

The civic symbols depicted in the lower parts have great importance: the lily of Florence; the coat of arms of the Guelph party with the eagle clawing the dragon; the cross of the Florentine people; the bipartite shield and again the lily. The Opera di Santa Maria del Fiore was an institution created and financed by the city government, and as suggested by the iconography of this stoup, the Cathedral basilical space also had a civic function, as a covered monumental square.