From the Palacio de los Guzmanes it is a few minutes' walk along Calle del Cid (behind the Palacio), passing the Jardín Romántico, to the collegiate church of San Isidoro.
The church can be reached from the cathedral by following the well preserved old town walls (northeast of the choir), going north and then turning west. The walls, which date in part from the third century A.D. and are reinforced by numerous round towers (cubos), lead to one of the old town gates, the massive Puerta del Castillo (1759), southwest of which, by way of Plaza del Castillo, is the Plaza de San Isidoro.
The square is dominated by the Colegiata de San Isidoro, which originated as a 10th Century church but which was completed in its present form in 1149. It is of great importance to Spanish Catholics as the last resting place of San Isidoro, bishop of Seville and the greatest Visigothic doctor of the church, whose remains were brought here from Seville by Ferdinand I in 1063. At the west end of the church rises a massive Romanesque tower. The finest features of the exterior are the two Romanesque doorways on the south front, which faces on to the square: on the left the Puerta del Cordero (Doorway of the Lamb), the main doorway, with sculptured figures of San Isidoro and San Pelayo and the Lamb of God, and on the right the Puerta del Perdón, with a relief of the Crucifixion.
Colegiata de San Isidoro - Interior
The most notable feature of the rather dark interior is the 16th century Capilla Mayor. In the north transept are the Capilla de San Martín and the Capilla de los Quiñones, which has Romanesque frescoes.
Colegiata de San Isidoro - Treasury and Library
The Treasury and the Library contain many valuable items, including (in the Library) a Bible of 960, a 15th century breviary with miniatures by Nicolás Francés and the embroidered "Banner of Baeza" and (in the Treasury) the 11th Century reliquary of San Isidoro, the agate Chalice of Doña Urraca (11th C.), a casket decorated with Limoges enamels and a processional cross by Juan de Arfe.
Colegiata de San Isidoro - Royal Pantheon
The highlight of a visit to San Isidoro is the Panteón Real, the burial vault of the kings, princes and nobles of León, which was built on to the west end of the church in 1054-66. The groined vaulting of the Pantheon is borne on two marble columns which, like the columns round the walls, have capitals carved with plant and animal motifs. The ceilings and vaulting along the east and south walls are covered with superb frescoes painted in the reign of Ferdinand II (1157-88). The glowing color of these paintings, which depict Biblical scenes, hunting scenes and the labors of the months, interwoven with animal and plant ornament, have earned the Pantheon the name of the "Sistine Chapel of Romanesque art".