Located in Piazza dei Cavalieri, the building has changed names over time depending on the judiciary which has hosted: by "Building of the Archive of the Chancellery" in the Middle Ages to the "Priori Palace" after the conquest by Florence (1409), to "Palace of the Council of the Twelve" when it passed in the hands of the Order of the Knights of St. Stephen.At the end of the sixteenth century, the palace was renovated by architect Pietro Francavilla (sculptor of the Statue of Cosimo I in front of the nearby palace of the Knights too), who conformed it to the surrounding buildings for height and style of decorations of late Renaissance. The frieze on the cornice recalls how the work was completed in 1603 under the Granducato of Ferdinand I de' Medici. The transition to the Order of the Knights came only in 1691, when the priors moved to Gambacorti Palace: here the knights established their court, as also noted the inscription on the main portal. 

The facade is today characterized by a plaster on which stand white marble decorations: the window frames, the portal flanked by two columns, the balaustrate openings of the main floor, the cornices, the arms, the corner reinforcements and the cornice.Inside there are numerous works of art, such as the sixteenth-century bust of Ferdinand I, the fragment of a fresco of the Assumption of the school of Domenico Ghirlandaio (first floor, Sala degli Stemmi) and especially the hall of the audience, with the walls completely painted by Pietro Paolo Lippi and Antonio Giusti (1681-1683) with a maritime theme and the remarkable ceiling carved, gilded and painted with the cardinal virtues by Ventura Salimbeni (1602); now at the center of the ceiling of the room is the Triumph of St. Stephen by Giovanni Camillo Gabrielli (1692), which replaced the Triumph of Pisa by Salimbeni after the building became the property of the Order.