The Sanctuary of the Holy Trinity is an important destination for devoted pilgrims. The 5th-century building stands in Vallepietra and was partly carved into the rock face of Mount Autore at an altitude of 1300m.
The are various theories concerning the origins of the Sanctuary. There are two legends, one of folk origin and the other literary. The first tells of a farmer who was tilling the land at the top of Tagliata hill. He saw the ox and plough fall over a precipice. On arriving at the bottom of the huge rock face, he was amazed to see the ox kneeling in front of a mysterious painting of the Trinity that had appeared in a small grotto. The plough was left higher up, caught on a rocky overhang.
The second, literary-based legend was written on a scroll that was later destroyed. A copy however survived. According to this story, two people from Ravenna, who were living in Rome, climbed Mount Autore to escape Nero’s persecution. Here they were visited by the Apostles Peter and John who had crossed the Kingdom of Naples after landing at Francavilla. An angel appeared to the four people bringing food from heaven and making water spring forth from the earth. The following day the Holy Trinity appeared and blessed Mount Autore, declaring it as sacred as Mount Sinai and the holy places of Palestine. 
Legends aside, various theories have been put forward about the origins of the Sanctuary. Some scholars believe the origins of the place of worship dedicated to the Holy Trinity on Mount Autore, directly above the source of the Simbrivio River, can possibly be traced back to Eastern monks or hermits. The Greek-style blessing pose of the “Three People” worshipped at the Sanctuary and the particular place names in the surrounding area may support this hypothesis. The mountain in front of the Sanctuary was called Sion right up until the last century and the closest town, on the Abruzzi side, is Cappadocia (like the Eastern region). Another theory suggests St. Dominic of Sora founded the Sanctuary of the Holy Trinity.
The most noteworthy fresco in the Sanctuary is the one depicting the Holy Trinity. The chapel that holds the venerated image in the Sanctuary has also other frescoes, the oldest of which are on the east wall. On the upper part of the wall, they depict the Trinity and scenes from the Gospel (Annunciation, Nativity and Adoration of the Wise Men, Presentation of Jesus at the Temple).  On the lower part of the wall, there are two scenes showing the months of January and February. These paintings were probably the remains of a cycle illustrating the work that was carried out in different months. Originally, they would have decorated the lower walls of the Sanctuary. On the top left of the wall at the back, you can see the face of a saint with a shining halo, identified as either St. Bernardino of Siena or St. John of Capistrano. Two Virgins and three saints are painted on the east side of the Sanctuary.
A highly suggestive pilgrimage is made to the Sanctuary on the Sunday following Pentecost.

Galleria fotografica