The city of Piazza (as it was called before 1862) originated during the Norman domination in Sicily (11th century), when Lombards settled the central and eastern part of Sicily about 900 years ago, but the area was inhabited since prehistoric times. The city was flourishing also during Roman times, as shown by the notable mosaics at the patrician Villa Romana del Casale.
The town is famous chiefly for its Roman mosaics in the Villa Romana del Casale, about 3 kilometres (2 miles) to the southwest. It has a range of significant architecture dating from medieval through the 18th century. The discovery and excavation of the well-preserved, highly refined mosaics has helped attract tourists.
The medieval history of the city is manifest in some of its houses, which show Norman or Gothic architecture. The main landmarks include a range of architectural styles:
The massive Baroque Cathedral (17th and 18th centuries), built on the 15th-century foundations of a former church, from which the bell tower was taken and reused. Also original to the 15th-century church are the Catalan-Gothic style windows on the left side. The dome dates from 1768. The façade has a notable portal with spiral columns by Leonardo De Luca. The interior, with a single large nave, houses the Madonna della Vittoria (Madonna of the Victory). The Byzantine icon is traditionally associated with the banner donated by the Pope to Roger I of Sicily during the Council of Melfi. The cathedral has an unusual two-sided crucifix by an unknown artist. The Diocesan Museum holds reliquiaries, articles of silverware, monstrances and other religious art works.
The nearby Palazzo Trigona, house of the wealthy family who commissioned the church.
The Church of Fundrò, known also as St. Roch, with a carved tufa portal.
Piazza Armerina is one of the so-called "Lombardic" communes of Sicily, as its dialect differs notably from that of the neighbouring region. This is due to the destruction of the old Piazza by king William I of Sicily, and the subsequent repopulation by William II (according to other scholars, during the slightly later age of Frederick II) with colonists coming from "Lombard" regions of northern Italy, especially from Monferrato and Piacenza.