Stage 1: Agüero – Riglos


The Kingdom of Los Mallos

Some parts of the first Stage of the Nature Trail of La Hoya de Huesca, one of the two towns in Aragón most well known for its sheer rock formations or mallos on touring the municipalities of Agüero, Murillo de Gállego (Zaragoza) and Las Peñas de Riglos, coincide with the GR-1. It begins in the town of Agüero, which is located in the extreme northwest of the region of La Hoya de Huesca, at the foot of its impressive mallos. These geological formations, which are characteristic on account of their cylindrical shapes and vertical walls of Miocene conglomerates, bear this name in the whole of the Pre-Pyrenees of Aragón. The mallos of the neighbouring town of Riglos, the end of the first Stage of the Nature Trail, stand out because of their size and importance.

Vista de la localidad de Agüero a los pies de sus Mallos

The path leaves from the town’s main square, where you will find the parish church of San Salvador, declared a Site of Cultural Interest, whose Romanesque façade featuring Christ Pantocrator stands out. Continuing in an easterly direction towards the bakery, the path goes along the steep streets of the rural centre towards the ravine of the fountain of El Piojo. A short while before you leave the village, the path turns to the right towards a small rest area in the bottom of the ravine, located next to an old stone fountain. Other attractions that you can find in the narrow streets of Agüero are its Ethnological Museum of d´o Sagallo and the olive tree of Chiménez (Olea europaea), a specimen from the catalogue of unique trees of Aragón, which is several hundred years old and was divided in two by a flash of lightning.

A little further ahead, there is an informative panel for this first Stage of the Nature Trail, which continues by crossing the ravine and ascending via a path in poor condition between kermes oaks (Quercus coccifera) and almond trees (Prunus dulcis) as far as the road that leads to the top part of the village. After walking along an asphalted part for some 150 m, you reach a sharp bend where the path turns to the right along a track with directions to Murillo de Gállego and Riglos, coinciding with the GR-1.

Portada de la Iglesia de Santiago de Agüero

From here, you will have a beautiful view of the mallos of Agüero, which are a little less known than their neighbours in Riglos, but equally impressive. Worthy of note is the Peña Sola, separated from the other mallos on the left of the massif, as it is the one that is most frequently used by climbers and because the remains of the old castle of Los Mallos, a Building of Cultural Interest currently in ruins, is located at its base.

Leaving the mallos behind you and Peña Rueba in front, carry on for some 400 m when the path turns to the right to cross an area in worse condition which, a little further on, turns into stone, the remains of a mediaeval road, which descends as far as the ravine of Espadiero. At the bottom of the ravine, a very large Holm oak (Quercus ilex) gives shade to the rest area behind which the trail returns to the track turning to the right.

On the right of the route, hidden behind a Holm and kermes oak-covered hill, you will come to the church of Santiago, catalogued as a Building of Cultural Interest, which is accessed by leaving Agüero along the HU-534 highway, at a signposted turn-off on the left, following a track for around 1 km. It is an unfinished construction from the sculptural workshop of the maestro of Agüero, whose work can be found in other places in Aragón such as in San Juan de la Peña and San Pedro el Viejo in Huesca.

Paredón de Peña Rueba en Murillo de Gállego

On making headway between fields of almond trees, approximately 1 km along the trail, coinciding with the route of the GR-1 trail, the path turns to the right along a stony path which descends among kermes oaks, crosses a small stream with stepping stones and once again climbs up to the track, among almond trees and herbaceous crops until the path turns towards the left on a sharp bend some 600 m further on. The trail turns once again into a path and heads in the direction of Murillo from Gállego, which you can already see in the distance, together with Peña Rueba, which continues on your left. This geological formation, similar to the mallos, is outfitted on its southern face with sports climbing and ferrata routes, and is the nesting place of numerous birds, many of which are carrion-feeding, such as griffon vultures (Gyps fulvus), Egyptian vultures (Neophron percnopterus) and bearded vultures (Gypaetus barbatus).

El camino acercándose a Murillo de Gállego con los Mallos de Riglos al fondo

The path with a little wall on the right, which has collapsed in parts, gives way to another stony area of mediaeval road, which begins to descend, joining another larger downward path that is also stony, with the mallos of Riglos in the background and the village of Murillo de Gállego appearing before us in the foreground. The stony downward descent towards the bottom of the ravine of Bivera intensifies in the final Stage and trekkers are helped by two portions of wooden railing that lead the trail to some natural sandstone steps in the ravine bed.

The trail now runs along the left bank of the ravine and you can see on your left the entire thickness of the alluvial terrace materials. In a few metres, at the entrance to the town of Murillo de Gállego, you reach the old Roman construction, where a cosy rest area with tables, benches and a panel with information on the path has been outfitted around it. From here, you climb towards the town centre along a paved street following the path’s signposts. Heading in the direction of the church between stone constructions with a marked mediaeval nature and after climbing some steps, you enter the square of the church of El Salvador, which has been declared a National Monument. In the high part of the town, you also come to the Romanesque chapel of the Virgin of La Liena that stands on a mediaeval necropolis containing tombs excavated in the rock. In Murillo, you can also visit the Electricity Museum located in the old Flour Mill.

Pasarela del Camino Natural sobre el río Gállego en Murillo

The path descends from the square to cross the road in the direction of the campsite and the River Gállego along an asphalted road surrounded by olive trees (Olea europaea). After leaving the campsite on your left and walking down to the river, you turn to the left along a dirt path that makes its way in the shade of Aleppo pines (Pinus halepensis), junipers(Juniperus communis) and kermes oaks (Quercus coccifera), Here, you enter the walkway over the River Gállego, where you’ll find an informative panel on the fauna, vegetation and geology of the area and the water activities that take place on the river.

The River Gállego is one of those with the greatest biodiversity in the province of Huesca. With respect to the fauna you can find in this Stage, worthy of note is the otter (Lutra lutra), which is gradually recovering its population thanks to the amount of fish there, such as the rainbow trout (Oncorhynchus mykiss), the common trout (Salmo trutta) and the common carp (Cyprinus carpio), in addition to water birds such as the Royal heron(Ardea cinerea) and the cormorant (Phalacrocorax carbo).

El río Gállego desde la pasarela de Murillo, con la Peña Rueba al fondo

The vegetation on the riversides is also plentiful and comprises poplars (Populus nigra), white poplars (Populus alba), willows(Salix alba), ashes(Fraxinus excelsior) and elm trees (Ulmus minor) together with bushes such as tamarisks (Tamarix gallica). The geology of this Stage of the river is also characteristic, as from the reservoir of La Peña as far as Santa Eulalia de Gállego, crossing the canyon of the River Gállego, you can see the transition of the marls to sandstones and conglomerates of the Miocene, which conform the unusual mallos. In addition to these natural values, the River Gállego also stands out for its suitability for water sports such as canoeing and rafting, which are promoting the development of the region.

The long pedestrian walkway built for the Nature Trail links Murillo de Gállego directly with Riglos, ensuring trekkers do not have to cross the river via the road bridge and shortening the distance between the two towns by around 5 km.

Paso a nivel del apeadero de Riglos y el mallo Firé

Once you are on the left-hand-side bank of the River Gállego, the path zigzags up to then pass over the projection of sandstones and marls excavated by the river, with the help of steps and wooden railings. In the top part, in the area of La Sarda, the trail turns to the left along a path following the 2.5 km sign to Riglos. From here, you can enjoy the natural spectacle offered by the mallos of Riglos, which, with their vertical red walls, rise impressively over the small village. A few metres further on, the trail joins the track that leads directly to the village. After crossing the ravine of El Chopo and another small ravine, surrounded by a green plant carpet with a clear Mediterranean influence, with a prevalence of kermes and Holm oaks, you come to the Riglos railway halt. The path crosses the railway track of the “Canfranero” via a level crossing and the track changes into asphalt as it approaches the impressive conglomerate walls.

Los Mallos de Riglos con las casas del pueblo a sus pies

The road continues across an area of olive trees where, next to the houses in Riglos, some enormous hundred-year-old olive trees stand out, some of which are even included in the catalogue of unique trees of Aragón. The trail carries on along the steep streets, passing by some schools, and reaches the road next to the car park, where there are several informative panels and various restaurants and bars where you can enjoy the rich gastronomy of the region.

This first Stage ends in this unique town which stands out on account of its impressive mallos, recognised for being one of the best places nationwide for climbing and mountaineering and for being home to one of the most important nesting areas for griffon vultures (Gyps fulvus). You can also visit the church of Nuestra Señora del Mallo, the 11th-century chapel of San Martín Arcaz centre for bird interpretation.



MIDE (Method for the Information of Excursions)

(Calculated according to the MIDE criteria for an average excursionist with a light load)


Further information

The Mallos of Riglos

In Aragón, mallos (from the Latin malleus, which means “mallet”) is the name for the cylindrical shape and vertical wall reliefs that appear in the Pyrenean front along the outer Sierras.

These reddish conglomerate formations were formed by the dragging of boulder-type materials, cemented by gravel and sand, towards the old depression of the River Ebro. There, the sediment settled, which was later raised by internal folding during the tertiary era. The distinct erosion of the different materials led to their current spectacular configuration, which is enhanced even more at dusk, owing to the intensity of the light on these walls.

The structure of these reliefs, some over 200 m high, does not go unnoticed by travellers and mountaineers, who, in the 19th century, wrote about these spots. These descriptions, together with the first photographs in the 20th century, contributed to the fact that the 1930s began to see not only great climbing feats on these cliffs but also accidents. Since then, almost 300 climbing routes have been opened on practically all the walls, while the mallos of Riglos are known on the national and international level as one of the best places for climbing.

The mallos are divided into two groups: the large mallos and the small or little mallos, and although some of their summits can be accessed by foot, others are inaccessible and you have to climb to conquer their tops.

Each of the mallos has a name linked to its shape, a house in the village or a local character or climbers, so, if you look at their south face from left to right, you have the large mallos: Firé, Puro, Pisón, Macizo, Volaos, Cuchillo, Frechín and Visera. Separated from the main massif and further to the right, we find the small mallos of Colorao, Chichín, Herrera, Magdalena, Cored, Gómez Laguna, Aguja Roja, Capaz and Arcaz or the Vultures’ Wall.

The most well known are those located over the village whose houses are positioned very close to their foothills, and which are also the highest: Firé, Puro, Visera, Cuchillo and Pisón, with the highest altitude and whose vertical wall has a difference in level of 275 m. On some occasions, these walls have collapsed, such as in La Visera, which makes climbing them even more spectacular.

The other great attraction of the mallos is the number of birds of prey that live on their walls, including Egyptian vultures (Neophron percnopterus), peregrine falcons (Falco peregrinus), wallcreepers(Tichodroma muraria), bearded vultures (Gypaetus barbatus), in danger of extinction, and above all, griffon vultures(Gyps fulvus), which form one of the largest stable colonies on the Iberian Peninsula and in Europe, with the Arcaz mallo or the Vultures’ Wall standing out as a protected nesting area where you can find between 70 and 100 nesting couples every year.


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