The Diocesan Sanctuary of Madonna del Monte (in Costa di Aviano) legally belongs to the parish of Marsure. The people of Marsur are particularly attached to this place which, according to tradition, stands on the site where the Virgin appeared to the farmer Antonio Zampara in 1510. The Sanctuary was consecrated in 1615 and made more harmonious in the early 1900s by the architect Rinaldo of Venice . Externally it is characterized by a large dome covered in metal; the interior, very bright, has a large lantern in the junction of which are placed the four stone statues depicting the evangelists. In recent years the sanctuary has also been enriched by a devotional path, and is chosen by numerous Christian communities for spiritual retreats.
The origin of the sacred place is lost over the centuries; there is talk of a chapel on Monte di Costa already existing in the first half of the 15th century. The turning point came on 8 September 1510 with the apparition of the Virgin to Antonio Zampara, a pious 79-year-old farmer. According to the story handed down, the man, very devoted to the Madonna, stopped every day in front of the chapel for his prayers before starting the day. One September morning, after reciting his prayers, he heard a voice sweetly asking him where he wanted to go. He replied that he was going to a friend to ask him to come and plow the land. The voice replied: “He will come willingly.” Then, raising his eyes, the man saw Mary, dressed in white, who said to him: "Come on Antonio, get up and don't be afraid. From you, who return to your home, I want you to observe a rigorous fast of three successive Saturdays in My honor." He invited all the inhabitants of the area to do the same and asked for the construction of a chapel and an altar. And so it happened.