The church is on the Greek Cross plan: it therefore has the same length and width at the transept. At about , it is one of the largest edifices with a central plan in northern Italy. The central dome, with an octagonal plan, is tall, with a total weight of some 20,000 tons. It is the fourth in Italy in size, after
St. Peter's Basilica, the
Pantheon and the
Cathedral of Florence. The monument is a large building. The church develops on three naves (the central double of the lateral ones and crossed by a practicable gallery), both in the longitudinal body and in the transept. The side aisles are flanked by semicircular chapels. The interior, with pure Renaissance architectural lines, gives an impression of great grandeur, amplified by the brightness of the very white marble cladding. On the counter-façade, two masterpieces of the Baroque period: Madonna and ss. Siro and Antonio, by
Giovanni Battista Crespi, known as Cerano, and Adoration of the Magi, by
Daniele Crespi. In the apse there is an imposing Baroque decoration, consisting of stuccos and frescoes. The structure depicts a radiant cave with golden clouds in the center of which two angels hold up a large crown of thorns. Around it there are cherubs and angels and on the sides two symbolic figures of Religion and the Fatherland. This plant surrounds the seventeenth-century reliquary in silver and crystal containing the Holy Thorns of Christ's crown. In fact, three thorns are preserved in the Cathedral, which according to tradition were found by
Saint Helena, mother of Emperor
Constantine, around 327. The thorns are lowered from above during the
Pentecost vigil to be carried in procession on following Monday. This tradition has been repeated since 1645. In the apse of the left transept, in the center, the Altar of the Confraternity of suffrage, built by the Genoese Tommaso Orsolino in 1644–46 and remodeled in 1652 with the addition of two columns and other elements of precious marble. In the apse of the right transept, the Altar of
Saint Syrus, first bishop of Pavia (III–IV century), with double front. Above the nineteenth-century crystal urn with the remains of the saint, there is a monumental ancona in white marble with an alabaster base from the Orsolino (1645–1650) depicting the Virgin delivering the keys of the city to
Saint Syrus. ,
Our Lady of the Rosary (1531). On the east side of the right transept is the Chapel of Our Lady of the Rosary previously dedicated to the passion. On the altar there is a canvas by the Pavese artist
Bernardino Gatti known as Sojaro (1530–1531) depicting the Madonna with the child, Saint Dominc and Saint Alexander. Fifteen episodes referring to the mysteries of the rosary are represented in the outline of the painting (to be read counterclockwise). In the left aisle, in the third chapel, there is an altarpiece depicting the
Immaculate Conception. painted by
Federico Faruffini on behalf of the canon Giovanni Battista Bosisio in 1857. At the foot of the Virgin you can see the outline of the city of Pavia, while on the architrave there is the inscription
Fecit mihi magna qui potens est. On the sides of the altar are the statues of the parents of the Virgin, Joachim and Anna. The remains of the bishop of Pavia Saint
Damian of Pavia (VII century) are placed under the altar. ==See also==