Ploaghe is a town of 4257 inhabitants and has an area of 96 square kilometers for a population density of about 49 inhabitants per square kilometer. It rises 425 m above sea level at the foot of an extinct volcano (Mt. St. Matthew). It was an episcopal see from 1090 to 1503, chief town of a curatoria in the Judicial period and then a center of baronial power.
The town retains signs of a past of great decorum: on a wide square in the center of the town are the parish church of St. Peter the Apostle, the Oratory of the Rosary, which houses the Spano Picture Gallery, the Oratory of Santa Croce, the parish house and the town hall. In the area there are numerous evidences of human presence since the Copper Age. In 1920, 57 nuraghi were surveyed there. One of them, the Nuraghe Attentu, was the subject of excavations in the 19th century by Canon Giovanni Spano.
Ploaghe shares with Sassari and Nulvi the tradition of the Procession of the Candlesticks (dedicated to St. Peter and Baby Jesus) but is the only municipality to boast as many as four outings.
