Excellent example of a cruciform church, possibly the first one of its kind ever built. It has the shape of a Greek cross, totally vaulted, a single nave, an apse and a portico forming two simetrical lower and narrower ends, and a crossing nave of equal height forming a balanced ensemble with the main one. It has a lantern covered by a hipped roof over the crossing of both.

Built around 940 by St. Rosendo in memory of his brother Froila, this small oratory of 8.5 x3.85 x 6m, built with large blocks of well cut granite, consists of three small areas communicated through horseshoe arches: a lobby covered with a horseshoe dome, a central nave of groin vault, both rectangular, and a horseshoe shaped apse inscribed in a square wih shell dome.

Small rectangular hermitage possibly built in the 15th century in which elements of one or several  High Medieval churches were reutilised, among which a magnificent horseshoe arch points out, of Visigothic trace, supported by impost capitals with a decoration that recalls the Ramiro art style, upon columns decorated and composed bases. It is also very interesting an Asturian type window with excellent openwork lattice in stone.

Although at present it has a single nave, originally it had three, separated by horseshoe arches and flat covering. It still has three apses with entrance arches and horseshoe shaped plan, covered with semi dome vaults in brick, inscribed in a flat chevet from which the central apse protrudes slightly. From all the basilics built in the 10th century and considered as Mozarabic, this one is the less Islamic.