Cantabrian architect Juan Ribero designed it from its conception to its completion before his death in 1598, and installed the tiles in the main chapel.

On one side of the nave is the altar chapel dedicated to the Virgen del Carmen, with a gate of the 17th century and neoclassical altarpiece.

The image of the Virgin, who occupied the center, and some angels disappeared because, at the beginning of Spanish Civil War (1936–39), suffered the ravages of people from the Popular Front government side.

At the bottom, under the niche they occupy the Assumption, a group formed by the Santos Justo y Pastor and another with the Church Fathers, St. Augustine and St. Gregory.

In the previous altarpiece of 1537, late Gothic style, there were 12 panel paintings that allude to the life of the Virgin and Jesus, of which 6 are preserved.

The wall of the left aisle there is another baroque altar dedicated to Mary Immaculate, angels fit the typical image.

On the floor are two tombstones, one alluding to the same Doctor Juan Gutierrez Sanz, "father of the chapel, where he celebrated the feast of the Immaculate Conception over forty years and offered a lamp and founder."