Cathedral of San Salvador, Oviedo

The Sudarium is a small, plain linen cloth, roughly 84 by 53 centimetres, without any image but marked by stains of blood and pulmonary fluid arranged as if it had been wrapped around a wounded head. Devotion identifies it with the sudarium mentioned in John 20:7, the separate face-cloth that Peter and John saw folded in the empty tomb.

Unlike the Shroud of Turin it bears no picture, and its interest is forensic rather than pictorial: investigators such as the Spanish Centre for Sindonology have argued that its stain pattern, blood group and the placement of the wounds correspond to those on the Shroud, suggesting the two cloths covered the same head. Sceptics answer that the correspondences are loose and that the cloth's traceable history begins only with the medieval Asturian record, not in first-century Palestine. The Church venerates the Sudarium without ruling on its authenticity. It is shown to the public only three times a year, on Good Friday and on the feast of the Triumph of the Cross (14 September) and its octave, when it is carried in procession through the cathedral.

The Camara Santa was built by Alfonso II the Chaste in the early ninth century as the reliquary chapel of his palace at Oviedo, then the capital of the small Christian kingdom of Asturias that had survived the Muslim conquest in the mountains of the north. It is a two-storey structure: a lower crypt dedicated to Saint Leocadia holding royal tombs, and an upper chapel of Saint Michael holding the relics. In the twelfth century its walls were lined with a celebrated set of column-statues of the apostles, among the finest Romanesque sculpture in Spain.

Around the chapel the kingdom's craftsmen produced the great goldsmith's works that still sit in it: the Cross of the Angels (808), emblem of the city of Oviedo, and the jewelled Victory Cross (908), emblem of Asturias. The chapel and its treasury were largely destroyed by a dynamite explosion in October 1934 during the Asturian revolution, and several crosses were smashed and their gems scattered; the structure and the metalwork were painstakingly reconstructed. In 1998 the Camara Santa was added to the UNESCO World Heritage listing of the pre-Romanesque monuments of Oviedo and the Kingdom of the Asturias.

The present cathedral, a Flamboyant Gothic building with a single soaring tower, was raised over and around the old palace chapel between the fourteenth and sixteenth centuries, keeping the Camara Santa embedded in its transept. Because Oviedo held such concentrated relics of the Saviour, a medieval saying held that a pilgrim who went to Santiago de Compostela but not to San Salvador honoured the servant and neglected the Lord, "Quien va a Santiago y no al Salvador, visita al criado y deja al Senor."

The San Salvador route linking Leon to Oviedo became a recognised branch of the Camino de Santiago, and pilgrims still divert to the cathedral to venerate the relics before continuing north-west to Compostela. The cathedral remains the active metropolitan seat of the Archbishop of Oviedo, and the Sudarium is among the most closely studied of the claimed relics of the Passion precisely because it offers a physical object with a long, if not first-century, record.