At the centre of the upper register, a majestic figure in a red robe sits enthroned beneath a golden arch, his right hand raised in blessing and his left holding a sceptre, flanked by the Virgin Mary on his right and John the Baptist on his left. Mary, crowned and dressed in deep blue, gently turns a book’s pages, while John, in green, cradles an open volume and gestures toward the enthroned figure. The far left and right panels show Adam and Eve standing nude within shallow niches, their bodies rendered with striking realism and subtle modelling of flesh tones. In the lower register, the central panel unfolds a lush green landscape where crowds of figures in varied costumes gather around an altar bearing a lamb, its blood flowing into a chalice, while a radiant sun glows above distant towers and trees.

Angels in white attend the altar, and groups of saints, clergy, knights, and pilgrims converge from all sides, their faces individualized and their garments meticulously detailed. A fountain in the foreground sparkles, and the grass is dotted with tiny flowers, painted with minute precision. The composition is balanced by the arrangement of figures and the recession of the landscape, with crisp contours and a luminous palette of greens, reds, golds, and blues.

The brushwork is fine and smooth, with subtle transitions of light and shadow modelling each form, and the architectural frames of the panels are rendered with illusionistic detail. Above the main figures, smaller panels depict prophets and sibyls, while the Annunciation is shown on the upper wings, with Gabriel and Mary separated by a central column and rendered in pale, silvery tones. The lower wings, when closed, display grisaille images of St John the Baptist and St John the Evangelist, and donor portraits of a man and woman kneeling in prayer.