Its theme, derived from the popular 13th century book on the lives of saints by Jacobus de Voragine, the Golden Legend, is the triumph of the True Cross – the legend of the wood from the Garden of Eden becoming the Cross on which Jesus Christ was crucified.

This work demonstrates Piero's advanced knowledge of perspective and colour, his geometric orderliness and skill in pictorial construction.

Although the design of the frescoes is evidently Piero's, he seems to have delegated small parts of the painting to assistants, as was usual.

Left side, from the top: Right side, from the top: The main episodes depicted are: Piero diverged from his source material in a few important respects, including the story of King Solomon's meeting with the Queen of Sheba in a chronologically inaccurate place and giving greater emphasis to the two battles in which Christianity triumphs over paganism.

The cycle ends with a depiction of the Annunciation, not strictly part of the Legend of the True Cross but probably included by Piero for its universal meaning.