The Cardinal to who the monument is referring to is Gaillard de la Mothe, nephew of the Archbishop of Bordeaux, Bertrand de Goth who became the famous Pope Clement V at the beginning of the 14th century. This one grant his nephew the title of “Cardinal of Sainte Luce”, the first dean of the chapter of Augustinian canons (more info here) and a luxurious and comfortable home today known as "Palais Cardinal".
The ruins of the facade that are still remaining today reminds us that this beautiful palace was built from the 12h century on. Indeed, roman artistic elements are present: arch for openings with arches show geometric and floral decorations; the twin bays and neat decorations similar to other monuments of the medieval city from the early 12th century. The presence of pipes to the latrines certify some comfort in this edifice.
These details make us say that the first goal of this edifice was not defense but displaying a some wealth of the city in the eyes of sellers and pilgrims in transit in Saint-Emilion. The walls of this palace, still visible today, are part of a wall around the city (more info here), which was built along with the Palace ...You can admire the ruins of the Palais Cardinal in free access from outside of the city, do not hesitate to descend into the moat to see more closely the outputs of latrines ...!