Of the original monument, which dates back to the 16th century, some of the ironbars remain (curved, ending in a serpent's head and fitted with a ring), similar to the Manueline pillories.
Aesthetically renovated during the reign of D. Maria I, it was then endowed with a unique finishing touch, a royal crown. This one, sculpted in limestone, shows a diadem decorated with precious jewels topped by florets from which emerge pearly stems of double curvature which converge at the top into a crucifer.