Martyrial double plan building following a design that comes from the Roman world, in which the lower part is used for burials and the upper part for worship. In Spain there are precedents at least since the Paleo-Christian art, since we find structures of the same type in the Mausoleo de la Alberca in Murcia, Santa Eulalia de Bóveda, although in this last case it is not a martyrial building, and La Cripta de San Antolín in Palencia, Visigothic of the seventh century. This model will reach its maximal expression within the High Medieval Art in the palace of Santa María del Naranco, also built in Oviedo some 50 years later than the Holy Chamber.

Though the chronicles of the time do not mention it until the one of Silos, from the beginnings of the twelfth centurry, both its structure and bond, based on rough ashlar, like the Tower of San Miguel, to which is attached, locate the construction during the reign of Alphonse the Second, the Chaste, at the beginnings of the ninth century, probably as a palatial chapel. The higher plan was modified in the twelfth century to make the nave higher, replacing the original flat roof by a barrel vault, supported by fajones arches that lean on six double columns, decorated with the apostles, one of the most interesting group of sculptures of Spanish Romanesque. Unfortunately, as it also happens with many other Pre-Romanesque monuments it suffered wild barbarity in Asturias in 1934 causing serious damage. It was rebuilt between 1938 and 1942.

The lower plan, devoted to Santa Leocadia, which remains, together with Santa Eulogia's were brought later from Córdoba by Alphonse the Third, is a rectangular nave of 10m long by 3m wide covered with a barrel vault in brick, 2,60m high that, as well as the Crypt of San Antolín leans on a stone plinth attached to three of its sides. On each side two windows of great embrasure and a linteled door open to the outside but with a small embrasure towards the interior. There is also a small window in the chevet within a round arch upon columns and capitals that also frame a small tabernacle, forming an ensemble that recalls the chevet of San Antolín. Rests of inner door supports have been preserved placed on the floor, in front of the area dedicated to the altar, and some tomb stone plaques; among them, the cover of the Visigothic tomb of Itacio,one of the most interesting ones of that period. It is obvious that this lower plan was located at the floor level, with direct access through the doors at each side, and probably in a cemetery, as is the case of the constructions of this type of previous periods, even in the Carolingian, as some graves of the tenth century appeared on its surroundings during the excavations.

The higher plan, devoted to San Miguel as it was usual for this type of buildings, consists of a nave and an apse. Very little rests of the original nave since as we have commented already, it was modified in the twelfth century. We know it was higher than the apse and it was covered by a flat wooden roof. However, the original presbytery has been preserved and its triumphal arch supported on semicolumns atached to a pilaster with capitals of Byzantine influence, maybe of a former period and reutilized here. This arch gives origin tothe barrel vault in brick that covers the chevet starting from an impost along the lateral walls. At the end there is a window framed by attached columns and capitals with the same kind of decoration.

In its interior lie the relics offered by the Asturian kings to the Cathedral of San Salvador that not longer exists since unfortunately the present Gothic cathedral was built upon it in the fourteenth century. It is one of the most importatn goldsmithing collections of the Middle Ages that are still preserved, including pieces of such importance as the Cross of the Angels (808), the Cross of the Victory, that was ordered by Alphonse the Third in the castle of Gauzón for the Cathedral of Oviedo in 908 or the Box of Agates, donated to the Cathedral by Fruela the Second in 910.

This building according to the reconstruction of the palatial monuments proposed by V. Hevia after the excavations, was supposedly attached to the tower that was at the right end of the palace palace that Alphonse the Second built when he moved the court to Oviedo, although it is not clear whether it was a court chapel where the relics were kept -which we think is more probable- or a martyrial construction surrounding a cemetery. At any rate, it seems unquestionable that it forms part of the structure of the court town designed by Tioda to become the capital of the new kingdom being created by that monarch, both for its type of construction, with rough ashlars with buttresses, that were enlarged in the modification of the twelfth century, as well as for the type of decoration, besides the fact it was attached to the tower of San Miguel, that was a part of that palace. However, we have to emphasize two very important points regarding the structure of the Holy Chamber: the blind arches decorating the extrerior walls, which was unusual in Spanish Pre-Romanesque art until it was of general use in the first churches of the Alto Aragonés Art. The other point is that the ground plan contains the first nave covered by a vault of Asturian art type, a kind of covering that until then could only be seen in the chapels of the chevets of the churches. Of course it was not a new system as we can find in Spain this kind of vaults from a much earlier date, but until then the Asturian architects had only dared to use it for small spaces. This facts makes of the Holy Chamber a clear precedent of the building of the Ramirense period, in which Santa María del Naranco repeats part of the model, though also vaulted in the higher plan and with a much higher quality in its constructive style and scuptural decoration.

Nearest friendly lodgings of Asturian Pre-Romanesque Art