In the castle courtyard, called the parade ground, stands the small church of Regnos Altos, whose chronology is still hotly debated today. The building was originally dedicated to St. Andrew and changed its title in 1847, the year in which a small wooden statue of the Virgin called de Sos Regnos Altos was found among the ruins of the castle, with the dual reference to the elevated site of its discovery, Serravalle Hill, and to the high heavens. The present church is the result of several construction phases that occurred during the rule of the Malaspina, the Arborea and the Spanish era. It consists of a rectangular hall with a semicircular apse and two entrances: one on the facade and the other on the northeast side. In 1973, during restoration work, frescoes were discovered that proved to be of extraordinary importance in terms of iconography and style. Starting clockwise, at the top we observe: the Adoration of the Three Kings, the Last Supper, some Doctors of the Church, and the four Evangelists. Bottom: the Penitent Magdalene and a theory of Saints and Saints; on the wall opposite the apse, top: St. Martin giving the cloak to the poor man, bottom St. Constantine and St. Helen, with the instruments of Christ’s passion, St. Christopher, St. George slaying the dragon, Archangel Michael and the Celestial Woman; on the right wall, top, some Franciscan friars, and bottom, the legend of the three Living and the three Dead, the only representation of the island, and the Martyrdom of St. Lawrence. The work, dated 1340-1345, was commissioned by John of Arborea, brother of Marian IV. The authors remain anonymous, but because of the themes covered, the influence of the Franciscans is evident.