The castle of Monreale is located in the Municipality of Sardara about 50 kilometres north of Cagliari (South Sardinia), where it was built in the second half of the thirteenth century to guard the border between the kingdom of Arborea and that of Cagliari (fig. 1).

Nearby, at the foot of the hill on which the fortress stands, there are the thermal baths of Santa Maria de is Acquas, built in the area of the ancient thermae, known as Aquae Neapolitanae or Aquae calidae Neapolitanae. The Itinerario Antonino of Ptolemy placed them a short distance away from the road a Turre Karales, between Othoca (Santa Giusta) and Karales (Cagliari).

During the Roman period, a large spa complex was built on this site (fig. 2), of which a square pool (9.5 metres wide), interpreted as a natatio, and a smaller spa complex reused in the Middle Ages and in the Modern Age still remain.

Fig. 1 - The castle of Monreale and the spa area (transposition by M.G. Arru from Google Earth).

The latter building consists of a large rectangular room (A) with a barrel vault, housing two small rectangular pools and two swimming-pools on the North-East and North-West sides. Room A opens to the northwest onto another rectangular room with a barrel vault and apse.  

A door to the south-west of the A environment allows entering an ambulatory and then a small square room whose function is unclear (figs. 3-4).

Fig. 2 - Plan of the Roman baths (reconstruction by M. G. Arru from ZUCCA 1987, Table 27, p. 258).

Fig. 3 - Plan and sections of the main building (reconstruction by M.G. Arru from ZUCCA 1987, Table 27, p. 258).

Fig. 4 - Cross section of the main building (reconstruction by M. G. Arru from ZUCCA 1987, Table 27, p. 258).

The condition of the spa buildings during the nineteenth century is documented by a drawing published by Canon G. Spano, from which, however, it is not possible to understand what building techniques were used, i.e. if they were a simple opus vittatum or a mixtum (fig. 5).

Fig. 5 - Survey of the Roman baths published by Canon G. Spano (SPANO 1859, p. 21).

Several fragments of pottery have been found on the site, dating to a time span ranging from the first century A.D. up to the Medieval Age.

Near the spa, there is the country sanctuary dedicated to Santa Maria de is Acquas, built in the eighteenth century (fig. 6).

The necropolis of the centre of Aquae Neapolitanae was located about 300 metres to the southwest of the church in 1875.

Fig. 6 - Il santuario di Santa Maria de is Acquas (da http://wikimapia.org/1422765/it/Chiesa-di-Santa-Maria-de-Is-AcquThe sanctuary of Santa Maria de is Acquas (from http://wikimapia.org/1422765/it/Chiesa-di-Santa-Maria-de-Is-Acquas-o-Santa-Maria-Acquas#/photo/1057788).