The name Piazza derives from thè Latin term Platea or (Platia), that means "square, market". The appositive Armerina was added in 1862 because of thè proximity of the homonymous mountain. During the Middle Ages, it was conquered by thè Normans, in the person of Count Ruggero of Altavilla, who allowed the installation of a Lombard colony. In 1150, thè suburb was destroyed, and only in 1163 it was rebuilt by will of King Guglielmo I, who ordered thè erection of town walls and fortified towers. Under thè Aragonese dynasty, the first Sicilian Parliament was summoned in occasion of the Guerra del Vespro (war of the Vespro). In 1589, thè first University was established thanks to the influence of the Jesuits, that was operative until 1767, when this religious order was exiled from Sicily.