The Mozarabic churches of the Serrablo

The glacial valley of the Serrablo stretches south from Biescas and is home to many beautiful Romanesque or Mozarabic churches and to one of my favourite cycle routes.

The quiet country lanes have virtually no traffic and lovely views. The cycling isn’t too strenuous, the climbs are all nice and manageable ascents of 50 to 100 metres vertical, although the cumulative ascent soon builds up and there are a couple of short steep sections to test the legs a bit.

The real stars of the Serrablo are the wonderful churches. Each village has a medieval church built between the 10th and 12th centuries and they are quite rightly well known in Spain as one of the best collections of churches from this era.


San Pedro in Larrede, late 10th century

The churches are special as many have very original designs and have been altered little over the centuries. Normally, as a village gets bigger, the church gets modified and extended as the congregation grows. However, these villages got smaller over time, rather than growing.

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Moorish Spain and the Reconquista

The Moors invaded Spain in 711 and soon took over the vast majority of the Iberian peninsula. A small band of Christian kingdoms hung on between the Pyrenees and the Pre-Pyrenees, and also along the northern coast – roughly present-day Asturias, Basque Country, Galicia and Cantabria. Al-Andalus, as the Islamic caliphate in Iberia was called, was a very enlightened society and both Christians and Jews were allowed to practise their own religions. However, there were restrictions on land-ownership, holding public office and additional taxes to pay for non-Muslims. This led to some Christians moving to live in the small northern Christian kingdoms and the population of these areas swelled during this period. The Serrablo churches were built as these kingdoms were getting more established and richer.

During the Reconquista or ‘reconquest’ of Spain, the borders of Aragon and other Christian kingdoms pushed southwards. Huesca was retaken in 1096 and Zaragoza in 1118. Zaragoza lies on the Rio Ebro – one of the largest rivers in Spain. Zaragoza had been ruled for centuries by the Romans and the Moors, both who had constructed large irrigation systems in the rich but dry agricultural lands surrounding the Ebro.

The Aragonese crown saw that people were living in the relatively poor farmland of the Pyrenees and avoiding the rich land of Zaragoza, where they could produce many more crops. They gave people lands and grants to move to Zaragoza and farm this much more fertile land. This caused a huge depopulation of the Pyrenees in the 12th century, with the villages in the Serrablo suddenly becoming much smaller and hence not needing, or being able to afford, grand extensions to their churches.

This left us with the beautiful original designs we can still enjoy today. We visit the churches on lots of our holidays that are based in Biescas, either hiking up to the abandoned village of Susin or taking a trip around the churches on the rest day on our Valle de Tena Explorer holiday.

Romanesque and Mozarabic features

The churches are described as Romanesque, as they have features copied from Roman constructions, or Mozarabic meaning that it has been influenced by Moorish architecture. Very evident in the churches of the Serrablo are ‘keyhole’ windows and doors with horseshoe arches that wouldn’t look out of place in Marrakesh.

Triple keyhole window in San Juan de la Busa. This window is used as the logo for the ‘Amigos del Serrablo’ , an association that helps take care of the churches and villages.

Another keyhole window this time filled with alabaster. San Pedro de Larrede.

A door with an almost horseshoe arch. This doorway also has patterns over the arch which to me look very much like the arabic writing you get  in so many Islamic buildings.

San Juan de la Busa – late 10th century

Standing on its own with beautiful views up the valley, San Juan de la Busa is one of the most atmospheric in the Serrablo. It still has a very original design with few modifications. It is not in a village and the theory is that there was once a small village surrounding it. When villages were abandoned it was common practice to reuse the stones of the houses in other villages, however, the church wouldn’t have been touched which explains why you sometimes find churches on their own.

The church is always open, so you can see the interior. Like all of these churches, it’s very austere inside without much decoration. The walls are bare stone and it doesn’t have a large garish gold altarpiece like many later churches in Spain.

There are many Mozarabic features – the doorway with its (nearly) horseshoe arch and alfiz (rectangular feature surrounding the horseshoe arch), the triple keyhole window and a semi-circular apse with blind arches. Every 24th June, there’s a romería (procession) to the church from the nearby village of Olivan and mass is held there. One year, we visited the church with a group just as they were finishing mass and they kindly invited us to share wine, cakes and all sorts of cured meats with them – it was great fun.

A very curious feature of all these churches can be seen if you have a pair of dowsing or diving rods. Stand at the back of the church holding the rods, walk forward and the moment you cross from the main church into the semi-circular apse the rods cross. I bought a set of rods to test this and it happens in every church around here that I’ve tried it on. This is due to underground streams passing directly under the church but why they placed the church exactly on that spot I’m not certain – perhaps it has to do with ley lines and the like.

The orientation of the churches is also interesting. They are all perfectly made and designed but don’t usually point directly east but slightly off. I’m certain that if the medieval builders had wanted to align them directly east they could have done but for some reason, they didn’t. One theory is that the church is aligned to where the sun rises on the saints day of the church. I’ve taken a compass and measured the alignments of half a dozen churches but they didn’t line up, however, while doing this I happened to meet up with the head of cultural sites for the area who was checking the churches to see if they needed any work, etc. I think he was a bit surprised to see this mad Englishman measuring and checking the alignment of these churches! He told me that they do think the alignment relates to the saints day but that the names of the churches have changed over the centuries as different saints have come in and out of popularity and the original names have been lost in the mists of time. Therefore, we can no longer check to see if this alignment theory is correct or not.

San Pedro de Larrede and the Serrablo interpretation centre

Just a kilometre or two from San Juan de la Busa lies another beautiful 10th-century church – San Pedro de Larrede. The pretty little village of Larrede also houses a small interpretation centre for the churches of the Serrablo. Inside you’ll find information boards with lots of details of the Mozarabic churches in the area – great news, the info is in English and French as well as Spanish!

San Pedro is late 10th century like San Juan de la Busa but features a tower (I presume this was added at a later date but I’m not certain). The layout of this church forms a Latin cross rather than most of the other churches. Originally the layout of the churches followed a strict 1:2:3 ratio to signify the holy trinity – the width is 1 unit, height 2 units and length 3 units. I have read a theory that before Aragon became a Holy See in 1066 that the churches had a ratio coinciding to the golden ratio that appears throughout nature in so many ways. I’ve taken a tape measure to lots of churches and I have to say that I can’t find evidence of this.

Another nice feature you can see at San Pedro are alabaster windows. Alabaster is used for the windows in lots of the Mozarabic churches and cathedrals in the area. Glass was a rare and expensive material in medieval times, while the biggest alabaster mine in Europe is on the banks of the Ebro river so was readily available here. If used in large windows it gives a low translucent light and the veins in the alabaster look wonderful – kind of like a medieval version of stained glass. The cathedral in Jaca or San Juan de la Peña are two good places to see large alabaster windows.

Other churches

There are many more examples of mozarabic churches in the Serrablo or nearby. Highly recommended to visit are the churches in Olivan and Oros Bajo in the Serrablo. San Bartolome and the ruins of the 11th century monastery of San Pelay near the village of Gavin. The jewel of Romanesque or Mozarabic architecture in the area is undisputably the incredible monastery of San Juan de la Peña, consecrated in 920 and built under overhanging cliffs – it’s a great place to visit.

The old outdoor laundry in the village of Sardas.

11th century Santa Eulalia in Oros Bajo. The belltower was used as a machine gun nest during the civil war as the front line was very close by during one winter.

11th century church with lovely traditional ‘losa’ stone roofing in Isin


  1. Graham Taylor

    That’s a wonderful article Phil

  2. Sandy Lawrence

    I loved reading your descriptions about these churches, and I can easily picture you with your tape measure checking on measurements and angles of stones and openings just like when you stretched out across meadows and rocks to get closeup photos of the wildflowers on the hikes you guided us on. thanks for sharing with us.


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