From the baroque door opened in the west wall of the wall one can access the atrium or galilee of the church, a structure that must have been built at the end of the 13th century, as well as the rose window located in the same wall, in charge of providing natural light to the central nave. This atrium is covered by ribbed vaults. Originally, it had two altars: one from the 16th century dedicated to the Holy Sepulcher, which has been restored, and another dedicated to the Virgin of the Angels, of which no vestige remains; in its place, a Gothic Calvary can be seen today.

The construction of the church was projected during the reigns of Ramón Berenguer IV and Alfonso II of Aragon, in the time of Abbot Hugo, around 1166. It was conceived in Romanesque style.

The plan of the church is basilical, with three naves and a transept. The two side naves are much narrower than the central nave. The north nave, attached to the cloister, is Romanesque and has a ribbed vault. The central nave is also Romanesque, but is covered with a pointed barrel vault. On the other hand, the south nave is Gothic, a reconstruction made by Abbot Copons around 1330. This same abbot also ordered the opening of the seven side chapels and built the great Gothic dome, octagonal in plan and with large windows, which was restored between 1979 and 1981.

Around the presbytery is the ambulatory, from which five radial chapels open. The two apsidal chapels located in the corners have direct communication with the transept.

In the presbytery the old altar table is preserved, formed by a large stone supported by four pairs of Romanesque columns. Inside the building two of its greatest artistic treasures are kept: the Renaissance altarpiece by Damián Forment and the royal tombs.