The Capilla del Santísimo houses an image of Our Lady, the Virgen del Sagrario, patron saint of Toledo. She owes her name to the fact that she is kept in the Sacrarium, the holy place, where the reliquaries of the saints worshipped in the Cathedral are kept.
The image of the Patron Saint of Toledo seated on a gold-plated silver throne, the work of Florentine Virgilio Fanelli in the second half of the 17th century, is a late 12th century statue made in wood. In 1465 the statue was coated in silver and its clothing was adorned with a gold hem encrusted with precious stones. The Virgin is seated with the Child, likewise coated in silver, on her knees. Her right hand is raised in a sign of blessing and she holds a ball with a cross in her left hand.
Tradition has it that the image of the Virgen del Sagrario, which was hidden by the Muslims who had occupied Spain, was discovered after Toledo was conquered by the Christians in 1085, when she rose from the water in the Pozo de la Virgen (the Virgin's Well) in the Cathedral's cloister, holding a lighted candle in her hand.
The Capilla del Sagrario chapel is the work of Juan Baustista Monegro, with traces of Nicolás de Vergara, his apprentice. Inside, the chapel is lined with marble from the quarries in Genoa, Estremoz, Granada, San Pablo de los Montes and Urda, among other places. The marble was carved by Bartolomé Abril and Juan Baustista Semeria. Bronze decorations by Alejandro Brache and Francisco Sánchez were added, as well as gilt decorations by Andrés Salinas. The chapel is square, with a cupola with pendentives that rests on the main arches built by Pedro de Luargçarate and Miguel del Valle. The cupola is painted by Eugenio Cajés and Vicente Carducho, using the fresco technique. It is divided into eight sections, with four tondos alternating on its base, one for each of the four Evangelists. Each pendentive is occupied by the following figures: St. Eugene and Isaiah, St. Eladio and David, St. Julian and Ezekiel, and St. Eulogio and Salomon. At the end of each main arch, a Doctor of the Church: St. Augustine, St. Ambrose, St. Gregory the Great, St. Athanasius, St. John Chrysotom, St. Gregory of Nazianzus, St. Basil the Great, and St. Jerome. The Chapel also houses many paintings hung in the oratories along the side walls, signed by Vicente Carducho, Eugenio Cajés and Carlo Saraceni, and dedicated to St. Bernard, St. Eugene, St. Ildephonsus and St. Leocadia.
The coat of arms of Cardinal Bernardo de Sandoval y Rojas (1599-1618), under whose mandate the Tabernacle was completed, is inside the Chapel. On the west wall stands the Cardinal's urn-mausoleum, facing those of his father and brothers.
The Capilla del Santísimo was opened on 20 October 1616, a ceremony attended by Felipe II, the Prince, his wife, the Infantes and the Grandees of Spain. The event was solemnized with a fortnight of festivities.