The little church of Regnos Altos stands in the courtyard of the castle, called the parade ground, the chronology is still strongly discussed. The building was originally dedicated to St. Andrew and changed its name in 1847, the year in which, among the ruins of the castle, a small wooden statue of the Virgin called de Sos Regnos Altos was found, with the double reference to the high place where it was found, the hill of Serravalle, and the high of Heaven.
The present church is the result of several construction phases during the lordship of the Malaspina, the Arborea and the Spanish period. In 1973, during the restoration works, the following were found of the frescoes revealed to be of extraordinary importance for iconography and style. The work, dated 1340-1345, was commissioned by Giovanni d’Arborea, brother of Mariano IV. The authors remain anonymous.
Today it looks like a single hall church, where the presbyterial area has been entirely rebuilt. The most recent studies have however proposed a dating of the building to the 12th century and a series of subsequent interventions during the 14th century.