At about seven hundred metres in the east of Agüero we will find a magnificent Romanic building which has always been an hermitage, although its magnificence shows that its condition of a hermitage is just a purely topographic impression. There are not any documents written about this temple excepting two reports belonging to some Episcopal visits. Because of the first visit we know that an Hidalgos of Santiago confraternity exists in Agüero since 1786; because of the second one we know how it is said to be in 1805 one of the fewest hermitages for veneration. The building was built built in the XII century; it was discovered and published by Ricardo del Arco in 1919 and San Vicente studied it in 1970. It consists on three apses. These three apses face to three empty spaces, which form the first stretch of the thee naves in the temple. A wall that covers the three communication arcs in this first stretch with the next one hastily enclosed it. Three-barrel vaults covered it. In the south side of this stretch the front door that led to the temple was opened. Bellas Artes recently renewed it.
     The first problem we face with is to know who this church was built by. Trying to know why this building was built and who ordered this work to be built is very difficult. It does not seem to be a royal foundation even a work due to a noble family in the area. We can only think that some soldiers or a monastery wanted to build this building. From these two options we leave out the first one so we cannot find any relationship between them. And referring to the second one as a hypothesis we will try to show the existing relationships between San Juan de la Peña and this area in Agüero.
     The Pantheon royal house in Saint John had received at the end of the XI century a great deal of proprieties in Agüero. Their owners gave them to different cenobies who later depended on the monastery. These were some territorial goods, which will not be mentioned any more due to the serious events, which finished with John's abbot. This monk governed the monastery until 1170 when he was left out and driven out from the Aragon kingdom. The cause of this event, in which Pope Adriano IV and Prince Ramón Berenguer IV of Aragon will have to intercede, is the bad administration and the high expenses due to the abbot Jon. In this time the wonderful Romanic cloister of the monastery is not going to be finished, and to save the cenoby from ruin Ramón Berenguer IV offers some donations. Santiago's church in Agüero could be another work due to this abbot, unfinished work as we can see when visited. The cause of its building would have been to get a major approximation to politicians. San Juan de la Peña's monastery has been left out of the capital's influence because the capital is placed in Zaragoza, although Huesca due to its situation in the Aragon Crown's ways is still a very important point. There in the town the cenoby has only a church and the nearest place is in Agüero. This church could have been the first stage to move the monastery to a nearer place to the monarchy. Apart from this, Santiago's church is related to some buildings placed in "Las cinco Villas", some dominions in San Juan de la Peña, which are finished between 1170 and 1191. The columns so typical of this temple in Agüero can be found in Puilampa church and in San Miguel de Daroca's one.
     Some works in Las cinco Villas have barrel vaults and Santa Marïa de Egea has the same type of apsidal cover. It is a vault with ten nerves. There will also be some connections among these areas in Santiago's sculpture in Agüero, very important and close to the gothic transition. The only tympanum built on the south front door has a beautiful epiphany. It is supported on two modillions with the shape of an animal with a man and a woman on its right side. In the Adoration of the Magus scene, Agüero offers a lovely proceeding for the epiphanies in the Italian Quattro cento. San Miguel de Biota's church and San Nicolás de Frago's church have the same kind of tympanum. Both of these churches are situated in the area of "Las cinco Villas". In this portal there is a very nice collection consisting on nine capitals which were placed in two different phases, where we can see some centaurs scenes some wild animals devouring their captures, fights among gentlemen and the famous theme of the dancer. We can also see on the below part of the portal some fights among warriors, fights where the Mussulman is showed with a round buckler and the Christian is showed on a horse with one with a tip shape. The famous dancer, work designed by the one called magisterial of Agüero and who has nothing to do with the known San Juan de la Peña's magisterial is a common theme in "Las cinco Villas, Biota, El Frago and Egea, in a capitol in San Pedro el Viejo in Huesca and in a scene of the Romanic apse in La Seo in Zaragoza. It shows Salomé in one hand beginning the dance with a harpist and on the other hand in an incredibly distortional attitude with her hair on her face with a soloist with a sharp-pointed cap who was with her
     Inside the temple, in the central apse there is an arcade of arches, which tries to suppress the wall unsightly. There are mainly geometrical decorations with figurative elements as monsters holding some grapevines, some heads, and a curious face on the second capital on the right and a lot of geometric samples of knotted circles, which are similar to the details on the portal of Puilampa's church, building in which the magisterial Bernardo worked and which was finished before 1191. In the outside part of this central apse there is a sculptured impost which is similar to the one in the inside part placed on the epistle apse. This inside frieze which is scarcely fourteen centimetres high, tells about some scenes on Christ's' life, about his childhood and his birth. All the scenes are framed with leaves and fruit whose curves create a certain rhythm which give a movement sensation. The showed scenes are the following: the Annunciation, the Visitation, the Birth, the Magus Cavalcade to Belen, the Adoration to Jesus by the Magus, the angel's warning and the appearance in the temple. There is also a piece dedicated to innocent saints with Herodes ordering the slaughtering to the soldiers and with the help of some wise men who scrutinize Messiahs' birth in the ancient books. Then we can see the warning, which the angel gives to San José and the running of Sacred Family coming back to Israel. In this way would finish Jesus' childhood.
      To complete the temple we must mention the "canetes" and the inside capitals which are related with the ones in Santo Domingo de la Calzada.

      The four kilometres and a half are very hard to walk due to the narrow curves on the road, but as you get to the village the air freshness you breathe and the vegetation beauty on both sides of the road refresh you.
     There is a very closed curve which people who live in Agüero call the "second turn" gives us the Agüero's mallows' panoramic and the village on its feet.
     This is an impressive finding for people who do not know the route because of the great plastic beauty, which the join Mallows-village represents
     It is a natural location for a military defence; the documents related to Agüero date to the first Christian's time; everybody likes this square. There is a document, which tells about the Mussulmans' dislodging from the castle which Gallo I made in 1003. The military position was given to Sancho III the major from Navarra
     Agüero's castle had a great deal of vicissitudes especially in the Reconquest Age, because there are some documents in which it appears both, as a tenancy of the Aragon kings and occupied by the Arabic. It was a strategic defender point, which from the "Cinco Villas" led to San Juan de la Peña.
     The castle was located on the mallow's same ground between Peña Sola and the rest of the conglomerated mass. At the beginning it should have been formed by a wooden castle supporting a rocked wall, so on the walls some wooden vestiges exist. There are also several rooms which only one of them exists nowadays, a passage, which leads to the caves, and a reservoir with a canalisation to keep the rainwater.
     Between 1033 and 1165 the tenancy in Agüero had eleven seniors, being Jimeno Íñiguez the first one and Loferrench the last one. Both of them had the title of royal second lieutenant. Among them Fortún Íñiguez, died in 1089 is buried in the pantheon of San Juan de la Peña monastery. Despite the few visible residues the castle had a long life. Sancho III the major built it. There is a note in the book of the dead about a corpse who killed throwing himself from the high bramble ground in the castle where he was a prisoner. This castle was built at the beginning of XVII century.
     The castle church, placed at the castle foot on a big rocked block under Saint Miguel's evocation was also a parochial of the old Agüero establishment when it extended through the meridian lateral. According to the existing residues Saint Miguel had a regular plant with an only nave and a semicircular apse. Both, Saint Miguel and Saint Salvador monastery coexisted together. It was cited documentarily in 1892: Sancho Ramírez donates San Salvador monastery in Agüero to Saint Pedro de Siresa; later, the parochial church would be the one in San Salvador. It happens when the village is moved from its ancient location (on the castle base) to the outskirts of the new monastery. In this way it is sentenced that the population descent from the highest parts of the castle to the lowest parts of the castle. It happens the same thing in Loarre castle.
      This fact is testified by the name of the new suburb created (the most ancient in the village nowadays) and which is called "burniau" (contraction of burgo nuevo similar to the one in Jaca). Saint Michael's hermitage was demolished by an order given by Jaca episcopate last century, and its stone and rubblework were sold to a neighbour in the village who worked as a druggist according to the parochial books.