It was originally known as de Port'e Ponti, because it led to the bridge on the Tirso river, after which documents define it as 'of Saint Christopher', because a retable of the saint was kept inside it. The tower of Mariano, originally joined to the town boundary walls, today stands isolated in the middle of Piazza Roma, in Oristano, an evident trace of the fortifications that were lost. It dates back to precisely 1290, as is shown by the inscription over the pointed arch from which, during the Middle Ages, a portcullis was pulled down at sunset to close the entrance to the town. Every year, on Carnival Sunday and Tuesday, on the occasion of one of the most attractive and crowded events linked to the identity of Sardinia, Sa Sartiglia, the tower is an obligatory and evocative point of passage for the knights engaged in the equestrian joust.