Battle between Byzantine Emperor Heraclius and Persian King Khosrau II (detail), Piero della Francesca. Fresco, 329 x 747 cm. Last image in The History of the True Cross or The Legend of the True Cross, a sequence of frescoes painted by Piero della Francesca in the Basilica of San Francesco in Arezzo, Italy in 1452-56. It is his largest work, and generally considered one of his finest. Its theme, derived from the popular 13th century book on the lives of saints by Jacopo da Varagine, the Golden Legend, is the triumph of the True Cross – the wood from the Garden of Eden that became the Cross on which Christ was crucified. This work demonstrates Piero’s advanced knowledge of perspective and colour, his geometric orderliness and skill in pictorial construction.

Piero della Francesca (c. 1415 – October 12, 1492) was an Italian artist of the Early Renaissance. To contemporaries, he was known as a mathematician and geometer as well as an artist, though now he is chiefly appreciated for his art. His painting was characterized by its serene humanism and its use of geometric forms, particularly in relation to perspective and foreshortening. Most of his work was produced in the Tuscan town of Arezzo.