The spacious church clearly displays the characteristics of its style. It is of basilican plan with a nave and two aisles separated by square piers which support semi-circular arches and with a transept of impressive height. The iconostasis, that separates the sanctuary from the rest of the church is remarkably similar in appearance to a triumphal arch. The size and originality of the church stands out and distinguishes it from works of Visigothic art. However, without doubt, that which most attracts attention to this church is the pictorial decoration, with aniconic frescoes (stucco, very well executed), painted in three layers, with architectural decoration that bears clear Roman influences. Although it appears more a monastic rather than a royal church, a gallery was reserved for the king in the transept.
Of the three original entrances to the church, two have been filled in.
The only sculptural decoration that has survived to the present day is that of the marblecapitals on which rest the semi-circular arches. There are also two marble flagstones with hexagonal geometric figures and floral motives that are found in the central chapel.
The pictorial decoration is the most important element that can be seen in the church. It is without doubt the most important of its time, in its extent and conservation as much as in the variety of icons represented, in all of Western Europe.