After four centuries of almost complete neglect, Piero della Francesca is now one of the best known and best loved of all Renaissance painters - to such an extent that the route from one work to another has become the tourists' Piero della Francesca Trail. Sir John Pope-Hennessy takes a fresh look at the facts of Piero's career and the significance of his paintings. A clear chronology establishes the probable sequence of his activities in Arezzo, Borgo San Sepolcro, Monterchi and Urbino. In assessing the greatness of Piero's art, we need to concentrate on the works themselves: their structure, their theoretical basis, their use of mathematical research and the visual sensibility that was peculiar to Piero's own psychology. Only then shall we see them for what they really are.