The gothic collegiate church was erected from the foundation of king Casimir the Great between 1360 and 1382 when it was consecrated. t was probably erected on the site of an earlier building, as the western part of the chancel can be dated even at the beginning of the 14th century. Thanks to the care of monarchs and church dignitaries, the temple was flourishing and receiving privileges. On several occasions king Władysław Jagiełło visited it, and with his foundation, in 1423, the magnificent frescoes painted in the canon of Byzantine art were erected in the presbytery. The history of the collegiate is also related to the figure of the cardinal and the royal secretary Zbigniew Oleśnicki, who was a student of the collegiate school. It was the second in terms of rank temple after the Wawel cathedral, in the diocese of Kraków.
In the middle of the 15th century, on the south side of the chancel, a chapel of the mansionaries with vestry was added, while on the northern side a chapter room was added to the vestry. Then, until the mid-seventeenth century, only repairs were carried out which did not affect the spatial layout of the church.
When the retreating Swedish army blew up the castle in 1656, the fires damaged also the nearby collegiate church. The roof of the church, the western gable and a large part of the chancel vaults were destroyed. Fortunately the fire did not reach the collegiate interior. Since 1661 the collegiate chapter decided to undertake the renovation and reconstruction. The structure of the roof has been changed to gable roof, the floor-board and windows have been repaired. Murals in the chancel were to be renovated with the preservation of their ancient qualities, but that did not happen. In the years 1670-1674 the western facade was rebuilt and the porch was added. The work carried out during the eighteenth century concerned primarily the changes of the interior to the baroque decor. In 1818 the collegiate was raised to the dignity of the cathedral. The building was renovated in 1825 and again in 1886-1889 with the brick face exposed.
It is a hall-type building with a five-span, three-nave corpus with a three-sided ended, elongated chancel. Originally, however, the choir was rectangular, the three-side apse was added during the reign of Władysław Jagiełło. From the north side, a one-story sacristy, covered with a rib vault, was attached to it. Originally, each of the naves was covered with a separate gable roof, made of tiles. The elevations were reinforced with buttresses, between which the slender windows of the side aisles illuminated the central nave. Probably in the Middle Ages, all the windows had traceries, similar to those preserved in the bricked up windows in the presbytery from the south.
The interior was covered with a rib vault with bosses of heraldic decoration, whose program undoubtedly reflected the idea of a united Kingdom under the king Casimir the Great. There was also a rich floral and animal decoration of the friezes and capitals of the interiors. On the chancel walls survived polychromes made around 1421 by the rus workshop of master Hayl of Przemyśl. It is one of the largest and most valuable examples of this type of decoration in Poland.
Grzybkowski A., Gotycka architektura murowana w Polsce, Warszawa 2016.
Walczak M., Kościoły gotyckie w Polsce, Kraków 2015.
Website sandomierz.eparafia.pl, Historia katedry w Sandomierzu.