[1][2] The decoration on this apse is a noteworthy sample from the MNAC's unique collection of Romanesque mural painting, most of which comes from the diocese of Urgell.

In the apse there was a large representation of the Theophany, or manifestation of the Lord, inspired in the Gospel and the Book of Revelation.

Christ appeared in all his splendour, upright and imposing in the mandorla of his glory, with the Earth as his footstool, in keeping with the Biblical interpretation.

An attractive Greek fret in the classical tradition separates this register from the one below, in which are the Virgin and the Apostles, centred in the figures of St Peter, with the keys, and Mary, with a crown in her hand, a curious iconographic detail referring to the Kingdom of Heaven.

Also portrayed are Andrew, with the cross, a beardless John the Evangelist and Paul, the Apostle of the Gentiles, who represent the Church militant attending the manifestation of God.