The altarpiece of the main altar of the Basílica del Pilar was made of polychrome alabaster with a wooden dust cover by Damián Forment between 1515 and 1518, and is dedicated to the Assumption of the Virgin. Its architectural structure corresponds to the late Gothic style, but the scenes depicted show full Renaissance features.

In 1509, the chapter commissioned Forment to make the predella or bench of the altarpiece for the collegiate church of Santa María, on the condition that it be equal to or better than that of La Seo. Once this part was almost finished, in 1511 he was commissioned the rest of the altarpiece, which includes three large scenes: in the center, the Assumption of the Virgin; to the right, her birth; and to the left, her presentation in the temple. Forment delegated to other masters of his workshop the completion of the architectural elements and the whole was assembled in 1518.

The predella depicts seven scenes: the Meeting of St. Joachim and St. Anne, the Annunciation, the Visitation, the Adoration of the Shepherds, the Adoration of the Kings, the Pietà and the Resurrection. These are separated by Gothic columns that hold figures of saints and apostles. In this area Forment introduces details typical of the Renaissance, such as putti, cartouches and balusters. On both sides of the altarpiece there are statues of Santiago el Mayor and San Braulio in niches, and in the lower part there are coats of arms supported by angels and medallions. Although the original polychromy has been almost completely lost in the main scenes, it is still partially preserved in the predella.