Francesco di Giorgio Martini (baptized September 23, 1439 – 1502) is an Italian painter of the Sienese School, a sculptor, and a visionary architectural theorist; as a military engineer he executes architectural designs and sculptural projects and builds almost seventy fortifications for Federico da Montefeltro, Count (later Duke) of Urbino, for whom he is working in the 1460s, building city walls as at Iesi and early examples of star-shaped fortifications.