The church of Santa Eulalia de Erill la Vall is located in the heart of the Boí Valley, within the municipality of the same name, in the region of Alta Ribagorza, in Lérida. It is part of the outstanding group of churches built in the Lombard Romanesque style during the 11th and 12th centuries, an architectural trend that came from northern Italy and was perfectly adapted to the materials and conditions of this Pyrenean region. Santa Eulalia is one of the most representative of this style, not only for its architecture, but also for its elegance and verticality.

Like the other churches in the valley, this parish was linked to the bishopric of Urgel, which played a key role in the Christian consolidation of the territory. The archaeological and architectural research carried out in the temple have made it possible to reconstruct its constructive evolution with remarkable precision, confirming that it was built in the first third of the 12th century, although its history began in the 11th century. In 1962 it was declared a Historic-Artistic Monument and in 1982, an Asset of Cultural Interest. In November 2000, it became part of the World Heritage of Humanity by UNESCO, along with the rest of the Romanesque churches of the Bohí Valley.

The building has a single nave, long and narrow, with a chevet that adopts the triconque form, that is, three apses arranged in the shape of a clover: one main apse and two lateral apsidioles, located as arms of an incipient transept. Originally, the nave was covered by a wooden ceiling, although in the 12th century it was replaced by a continuous barrel vault that required the reinforcement of the toral arches. The access door opens in the north wall; it is semicircular, with voussoirs that preserve remains of polychromy in the intrados, evidence of the old mural decoration.

One of the most outstanding elements of the complex is the bell tower, attached later to the nave. It is a slender structure of six sections, clearly differentiated by imposts formed by blind arches and angles, a typical feature of Lombard Romanesque architecture. The twin windows open at the upper levels, contributing to its formal elegance. This tower follows the structural canon typical of minarets, where the height equals the perimeter of the base, a proportion that provides visual balance. Next to it, an open portico was also added, with semicircular arches supported on columns, which gives a more ceremonial dimension to the entrance of the temple.

During the excavations carried out inside the church, numerous original architectural elements were recovered, such as fragments of cornices, column bases and a truncated cone-shaped baptismal font made of limestone mortar. A permanent exhibition has been installed in the choir where some of these pieces can be seen, contextualized with information on the different construction phases of the building.

One of the most significant treasures associated with Santa Eulalia is the famous sculptural group of the Descent from the Cross of Erill la Vall. This masterpiece of Catalan Romanesque imagery was discovered in the early 20th century and is composed of seven figures carved in poplar wood: Christ descended from the cross, the two thieves, Joseph of Arimathea, Nicodemus, the Virgin Mary and St. John the Evangelist. The sculptures were originally arranged on a large central cross, as part of a scenic representation of the drama of the Passion, probably exhibited during specific liturgical dates. The figures, of great expressiveness and detailed work in the folds of the garments, reveal the technical quality and the symbolic load of the local sculptural school, linked to the barony of Erill.

This group is part of the boom that Romanesque sculpture experienced in Catalonia during the 12th century, especially in the Pyrenean areas. Many of these works were made under the protection of great local lords and prelates such as Saint Ramon, bishop of Roda. Coinciding with this flourishing of sculpture, the churches in the valley also produced splendid fresco mural decorations, such as those preserved in the churches of Taüll.

In addition to the Descent from Santa Eulalia, other carvings from different churches in the valley are preserved in the National Art Museum of Catalonia: an incomplete and smaller group of the Descent from Santa Maria de Taüll, a large image of the Virgin from the same church, a similar sculptural group from Durro and a carving of St. John the Evangelist. All these pieces constitute a valuable testimony of Catalan Romanesque art and of the intense artistic activity in the area during the Middle Ages.

Archaeological studies reveal that the temple went through several construction phases. The first, at the beginning of the 11th century, consisted of a shorter nave than the present one, topped by a truncated chevet. In a second phase, the nave was extended to the west and the present Romanesque doorway was built on the north wall. In the 12th century, the wooden ceiling was replaced by a stone vault, which required reinforcing the internal structure. Finally, the slender bell tower and the north portico were added, thus completing the image we can admire today. The church of Santa Eulalia de Erill la Vall remains one of the best examples of Lombard Romanesque architecture in the Catalan Pyrenees, both for its architecture and for the exceptional works of art it houses.