Its true name is Piazza Vigliena, as a tribute to the Spanish viceroy Juan Fernandez de Villena y Ascalon, yet it was also known under the name of Octagon of the Sun, because during the day the sun illuminates at least one corner of its architecture.
At its corners there are 4 convex facades of buildings of the 17th century and they are divided in three overlapping orders, with 4 statues representing the seasons on top of 4 fountains.