Le torri difensive con funzione di porta nelle cinte urbane medievali. La Torre di Mariano II a Oristano: ascendenze e derivazioni di una tipologia

The tower of Mariano II, also known as S. Cristoforo or Porta Manna, a symbolic building of the judicial city, stands today isolated in the center of Piazza Roma, in Oristano’s historic center. The only survivor of the two majestic towers-door of the turreted walls, erected by the will of the judge of Arborea Mariano II de Bas-Serra (the tower of San Filippo with a similar structure collapsed at the end of the nineteenth century and the remains were demolished in the early 20th century), is dated to 1290 thanks to the epigraph once placed above the rib of the ogival arch of transverse bipartition of the passage, which from the outside is practiced through the round front fornix. The tower (9.40 x 9.80 m) has a U-shaped planimetric system with three sides closed in thick masonry and the fourth open towards the town; 28 m high in total, it is composed of two separate and overlapping buildings, the first 19 m high (from the base to the first round of battlements) and the second, with the walls set back from the outer edge of the four which stands, is 10 m high. The wall faces are made of local sandstone ashlars of large and medium size, cut with perfect stereotomy. Up to an altitude of about 7 m, corresponding to the ground floor, there is a plinth made of ashlar ashlars, while the upper floors have smooth faces with the top floor crowned by Guelph battlements. The study, starting from a careful analysis of the construction techniques and the typological and functional characteristics of the tower-town gate typology, intends to highlight the particularities that together give the Mariano II tower characters of absolute originality. As far as certain affinities with some civic towers built in the same time range (second half of the 13th century) - both in the island area (Iglesias, Cagliari) and overseas, particularly in central Italy: Lazio (Barbarano Romano, Rieti, Viterbo etc.) and Tuscany -, derivations and contaminations ancestry have not yet been fully investigated