It is the most prominent Gothic church on the Cantabrian coast. Declared a Site of Cultural Interest in 1931, it became part of the Caminos de Santiago de Compostela: Camino Francés and Caminos del Norte de España World Heritage Site, inscribed on the World Heritage List in 1993, following its expansion in 2015.
In the 13th century, King Alfonso VIII commissioned the construction of this basilica-style church, accessed via a staircase flanked by two towers. It originally had three doorways, two of which are preserved. The main one, on the west façade, is framed by a large pointed arch flared by three archivolts and a canopy. The men's door, in the Classicist style, is later, having been built in the 18th century.
The interior is divided into three parallel naves and a polygonal apse. The central nave, twice the height of the side naves, has three floors: the first with arcades, the second with a triforium and blind arches, and the third with large windows.
The interior sculpture is rich and features plant motifs from the Cistercian tradition. The church preserves pieces of great interest, including two life-size polychrome figures: a wooden Gothic Christ from the early 14th century, and a stone Virgin from the late 13th or early 14th century. The altarpiece of the Holy Christ, in a pre-Churrigueresque style, with a painting by Zurbarán, is particularly noteworthy.
The style of the church is influenced by the French Gothic style of the Norman region and by Burgos Cathedral, which was built at the same time.
