Built in the mid-12th century, it is the only Romanesque church that has been conserved inside the walls. Constructed in Caleno granite, the building we see today conserves the imposing apse from its original structure, the northern enclosure and the materials that were reused in the 16th century for its reconstruction. The front is based on an archivolt decorated with four-petal rosettes and it stands as a reinterpretation of the original front that was taken down. The apse is broken only by two small columns and the corbels of the eaves; the decoration follows the Cantabrian Romanesque style.
Inside, despite the small size, it has three naves, with very narrow side sections, possibly adapted from an area that was originally designed as unique.
One of its most interesting features are the capitals that support the vault above the upper end: they are decorated with plant, animal and anthropomorphic motifs in pure Romanesque style.
The interior boasts the steps to the pulpit, made in one single piece of granite and decorated with waves that are reminiscent of its Visigothic connection.
It was designated a National Monument in 1923.