Serravalle Hill is a natural bastion overlooking the fertile river valley of the Temo, surrounded by pastures and forests, and Bosa, a medieval historic center that has earned recognition as the second most beautiful village in Italy, formed along the slopes of the mountain during two centuries between the 13th and 15th centuries (Rione Sa Costa). The enduring tactical excellence of its position, which allowed control of the territory from the sea to the river course to the urban settlement in the valley (Bosa vetus), is one of the factors that allows us to hypothesize how the site has been exploited over the centuries without interruption even if only as a lookout post to deal with sudden attacks by enemies (Saracens, brigands) or fires. Confirmed by archaeological excavations is the existence in Roman times of an urban settlement, the centerpiece of which would have become the early medieval cathedral of St. Peter located within the ‘bishop’s quarter,’ flanked by a Roman-based tower/belfry, with the nearby fenced cemetery. Belonging in the years around the year one thousand to the giudicato of Torres, the site in the late thirteenth century turns out to be in the hands of the Malaspina marquises (from Lunigiana) by marriage dowry (1232) and following the gradual decline of that kingdom. The present manor underwent numerous renovations made by the different owners (Turritani, Malaspina, Arborea, Aragonese), but on the whole it retains the defensive structure desired by the Tuscan-Ligurian marquises from the late 13th century, then forced to surrender their castles to the Aragonese, who had begun their invasion of the island in 1323: after 1365 they had lost possessions and political power. By 1317 the castle of Bosa had passed to the judges of Arborea, uneasy allies of the Crown of Aragon, in whose hands it remained until the end of the fifteenth century when their resistance was crushed by the Aragonese and Bosa was destined as a fiefdom to their loyal castellans, hardly ever at peace with the flourishing and proud Bosan ‘royal town’ (with communal-type statutes). Its decline began in the second half of the 16th century in favor of nearby Alghero, populated by Catalans. Of the Malaspinian block of the fortress, the defensive masonry enclosure with gorge-breaking towers, the keep (also gorge-breaking; height c. 20 m) restored in the late 19th century, and the patrol path of modern restitution are preserved. Inside, in addition to the palatine chapel, the ruins of the noble residence, also fortified, reserved for the castellans and their family, survive. Leaning against the north wall, it has a rectangular plan with four (originally) corner towers and a triangular ravelin: restoration indications roughly restore the division of the palace’s rooms. On the hill of Serravalle, within the walls of the castle known as the Malaspina family, is the small church dedicated in the late 19th century to N.S. de Sos Regnos Altos. Of Romanesque origins, it retained its medieval features (few and insignificant changes made in later centuries) until the late 19th century, when it underwent an eastward extension that destroyed the ancient apse. During consolidation work, a 14th-century fresco cycle, which had been lost to memory, came to light. All the walls of the medieval block were covered with it, a unique work in Sardinia. The frescoes can be dated, on stylistic and historical grounds (there are no reference documents), to the time when the manor belonged to the giudicato of Arborea from 1317 until the 15th century. In 1338 it had been inherited by John of Arborea, brother of Judge Marian IV, but the latter seized it in 1349 and imprisoned him there until both died of plague in 1376. Starting from the ‘ghost’ of the original apse and proceeding clockwise, (upper register, south wall) we encounter: Adoration of the Magi, Last Supper, Doctors of the Church and Evangelists. Lower register: procession of saints and saints recognizable by attributes and inscriptions. Lucia, Magdalena, Marta, James the Greater, Eulalia, Agatha, Agnes, Barbara, Victoria, Reparata, Margaret, Cecilia, Savina, Ursula. After unidentifiable figures, the procession continues on the counter façade (below) with Scholastica and finally Constantine and Helen. It is interrupted by the gigantic figure of Christopher, which, as is customary, spans the entire wall (mutilated at the top by the opening of a window in the Aragonese period). On his left is St. Martin and the poor man, and on his right is St. George and the dragon. Below, the theme of the Weighing of Souls (St. Michael the Archangel and the Merciful Virgin). On the northern wall we identify the first sanctified Franciscans: Clare, Anthony of Padua, Ludwig of Toulouse. This is followed by Imposition of the stigmata with Francis kneeling. Other unknown characters bring us back to the lost apse. Each illustrates the Franciscan virtues preached by the Saint of Assisi (humility, simplicity, charity, chastity, generosity, penance, courage of martyrdom). At the bottom the narrative closes with Martyrdom of St. Lawrence, but in the center of the wall is depicted Meeting of the Three Living and the Three Dead, the most remarkable painting in terms of pictorial quality and symbolic poignancy on the vanity of existence, a theme brought from the East by the Minorites themselves and spread to our country in the second half of the 13th century. Supported by the clarifications given to them by the monk Macarius (center), three dismounted knights (with a splendid falcon) look in surprise at three corpses lying in the tombs in different states of decomposition of the body after death. The first, above, has just descended into the tomb and keeps his fine clothes intact. In the center, patent is the advanced state of decomposition of the deceased (snakes, mice: symbols of a dark Afterlife). The third is now pure skeleton. The cycle run time can be set at 1340-45. Its patron was Giovanni d’Arborea, who called a Tuscan workshop to fresco his bare chapel, whose master builder was familiar with the ways of the great Florentine painter Buffalmacco, which nevertheless filters through a melancholy sensibility that refers to Sienese painting.
