Built on a conical high ground, along the southern border of the Judicate of Arborea, in the XII century. It was used for defence and look-out purposes.
The ruins of the Las Plassas castle overlook the nearby town. The etymology of Marmilla castle derives from the breast shape of the high ground where the fortress stands.
A number of conquerors settled in the fort: erected on the wishes of the Judge of Arborea, in 1409 it was conquered by the Spanish and made a feud in 1541 by the Aragonese, Acor Zapata, who became the feudal lord of Las Plassas, Villanovaforru e Barumini, where he took up residence.
The castle has an uneven hexagonal layout which meant the whole summit space of the bedrock was used. The double defence wall is still visible in the ruins as is the great tower and traces of the internal arrangement.
The findings uncovered during consolidation work and in the countryside during excavation are preserved and on display at the MudA civic museum.
