Four kilometres and a half from Agüero, walking through a runway in the forest, you can get to the aggregate to Agüero, San Felices. It is a very small village with seven houses, an abbey and church which is dedicated to Saint Mary, old castle and monastery in San Felices, documented in the royal chanceries texts. In 1042 Ramiro I gave the monasteries of Sásave and Castillón to García de Aragón, who was the bishop of Jaca, and between them it is mentioned "… and in the Extremadura the monastery of San Felices which is situated between Eliso and Castellmanco …"
      The church, under the invocation of Saint Mary is a romantic one, it has an only nave (modified in the XVI century), with a Romanesque arc in the entrance which support spires with floral ornaments inside three circles and a passant lion on the outside face; on the inside one there are some leaves, a pineapple and the classic chequered.
     The village is completed with some stockyards, parturition places an oven to cook bread, a blacksmithing and the near orchards. The church, which is situated on a boulder, has the confluence of the two cliffs (Artaso and Novillano), which from this moment will go together in the south direction (to Sancitol). The image of San Felices village from its access through the runway is similar to the one of the most sincere guardian of the way, which protected the access to everybody, who from the "Cinco Villas" (Fuencalderas - Biel) walked to go to San Juan de la Peña going through Salinas de Jaca … "(Cristóbal Guitart)".
     It is necessary to remark that the bishops of Pamplona and Jaca had many litigations for Agüero, Murillo, Eliso, Tolosana, Castellmanco, y Serracastiella it has never appeared San Felices in them, in spite of being, as it has been said before, between Eliso and Castellmanco, because it has always belonged to the Huesca diocese.
     What it is the tower of the church today, primarily was a defensive turret placed in a rock elevation as it was a prow in the confluence of two cliffs, (Artaso and Novillano leading the entrance way to the village and covering the village houses which are at its back.
     San Felices offers nature, peace and tranquillity to the visitor. It is altered not only due to the cattle, which grazes in the mountains but also due to the highest energy technology. Until 1999 San Felices did not have any light or running water. Nowadays a photovoltaic station gives some energy to the lighting system and to the monumental one as well. The installation of water able to be drunk has been the made work, which is added to the one of the electrification. In san Felices there are three inhabitants nowadays.