The High Altar, or Altar Mayor, occupying the centre of the apse, is approached by a flight of steps of white, red, and black marble. It is railed off from the ambulatory by _rejas_ or bronze screens fixed on pedestals of jasper between the pillars of the nave; the backs of these latter are adorned with life-size statues. Behind the altar rises the Renaissance retablo, an elaborate and gorgeous work of walnut wood, heavily gilded and each of its stages in a different order of architecture. The symmetrical division of these altar-pieces into compartments, each filled with its own statue, does not strike the layman as artistic or pleasing. Indeed, there is something faintly suggestive of pigeon-holes about it. Street, quoting Ponz, states that the sculptures were the work of Rodrigo and Martin de la Aya (1577), who were paid forty thousand ducats; and that for the painting and gilding Juan de Urbino of Madrid and Martinez of Valladolid received, in 1573, eleven thousand ducats. At the back of the sanctuary, between the arches, may be seen the spirited reliefs of the celebrated Juan Vigarni or ‘Borgoña,’ executed in 1540, and representing the Agony in the Garden, Christ bearing the Cross, the Crucifixion, the Resurrection, and the Ascension. The first and last are stated by Ford to have been executed by one Alonso de los Rios in 1679. To the Renaissance period also belong the handsome silver lamp and candlesticks. To an earlier age belong the tombs on the north side of the sanctuary--two concealed by the retablo; they contain the remains of Don Juan, the rebellious son of Alfonso X., Don Sancho, brother of Enrique II. of Trastamara, and his wife, Doña Beatriz. Over the altar is the copy of the banner borne before Alfonso VIII. at the Navas de Tolosa, made by the De la Aya brothers and others about 1570. Over the crossing or intersection of nave and transept rises the gorgeous lantern or octagonal dome, which Philip II. said seemed like the work of angels rather than of men. It replaced the earlier dome which collapsed in March 1537, and was completed in December 1567. Felipe Vigarni (de Borgoña) and Juan de Vallejo are mentioned as the architects. The Gothic and Renaissance styles are curiously but not inharmoniously blended in this beautiful lantern, which rises to a height of one hundred and seventy-three feet, and is profusely adorned with sculpture.