Guamaggiore (Gomajòri in Sardinian) is an Italian municipality of 882 inhabitants in the province of South Sardinia, in the subregion of Trexenta. The area was inhabited in pre-Nuragic (since the 4th millennium BC), Nuragic, Punic and Roman times, due to the presence in the territory of various archaeological evidence.
During the Middle Ages it belonged to the Giudicato of Cagliari and was part of the curatoria of Trexenta. At the fall of the Giudicato (1258) the territory passed briefly to the Giudicato of Arborea; Judge Mariano II in 1295 bequeathed the territories of the former Giudicato of Cagliari to the republic of Pisa, a fief of the Visconti. In 1324 the village passed to the Aragonese together with all the centers of the former curatoria of Trexenta and Gippi; in 1421 the village, with all the other villages of the former curadorìa dì Trexenta, was given in administration to Giacomo de Besora, who in 1434 obtained the feudal concession. In 1497 the village was united with the county of Villasor, a fief of Giacomo de Alagón. In 1594 the county was transformed into a marquisate.
The village was abandoned following the plague epidemics of 1651-55 and 1681. The survivors moved a little further north, where the present village stands.
In 1703 the fief was given by Artale de Alagón to his daughter Isabella married to Joseph da Silva. To the Da Silva – Alagon was redeemed in 1839 with the abolition of the feudal system.
From 1928 to 1946 it was aggregated, together with Ortacesus, to the municipality of Selegas.
