Definitely abandoned the city of Tharros, starting from 1070, Oristano became the new capital of the Giudicato of Arborea (10th century - 1410). The inhabitants of Tharros, in fact, tired of the continuous threats and incursions of the Saracen pirates, decided to move further inland and thus came to Oristano, an inhabited center that already existed in the Byzantine era. Immediately the new capital had a defense system that was strengthened at the end of 1200 by King Mariano II. This is the reconstruction of the city of Oristano at the end of the fourteenth century, equipped with three major towers located near the main entrances of the city and 28 minor turrets to strengthen the walls. To the north the tower of Mariano II, also known as Porta Manna or Porta Pontis, to the south the tower of San Filippo, identical to the first, connected to the palace of residence of the king and his court, to the east the tower of Portixedda, a small tower that it was born like the previous ones with a square base but which now has a circular base and a truncated conical shape, the result of a remake that took place in the Spanish era. A moat fed by the waters of the nearby Tirso river ran along the walls making this city even more conquerable which, rebuilt here, displays the most important religious buildings of the period: the Romanesque Cathedral of Santa Maria Assunta and its octagonal bell tower without the "Cipollone" in polychrome ceramic added in the eighteenth century, the convent and church of San Francesco, the Giudicale hospital, the church of San Mauro, the square-plan church of the Byzantine period dedicated to San Saturnino and finally the church and convent of cloistered nuns of Santa Chiara.