This Concatedral was built over a Romanesque primitive temple from the XII Century. Its name comes from its circular floor. In 1453, it became a collegiate church when it was joined to the San Martín de Albelda Church.
It has three naves and three polygonal apses. In its main faįade, there is a great stone altarpiece that is closed by railings that come from the Santo Cristo chapel. This facade appeared framed by slender Corinthian columns. The temple is divided into three naves and seven bays, and it is covered by a semi- dome in which you can see relieves of the four evangelists, four angels and the Everlasting Father. It suffered several reforms during the first third of the XVI Century and the XVIII Century.