The Tordesillas altarpiece has a "T"-shaped frame and continuous fretwork plinth at its foot with vesica pìscis patterned decoration on the pointed traceries. The altarpiece stands on a narrow predella of later manufacture decorated with plant motifs. Its structure is unique in that it has a double row of three reliefs combined with figures of the Prophets protected by poligonally-shaped canopies with hemi hexagonal bases of three sections combined at an angle of 45º with two other sections. This same structure is not continued in the lower level. Canopies have three levels: the lowest decorated with pointed arches and sharply-pointed gables, the middle with tracery decorating ogee arches crowned with rosettes and the upper decorated with lanceolated tracery. All have ribbed vaults and keystones.
Two painted wings split into four panels per wing protect the altarpiece: the larger panels have two vertical and horizontal sections while the smaller ones have a single compartment. Ogive arches and tracery decorate the top of the compartments.