Francesco di Giorgio Martini (1439–1501) was an Italian architect, engineer, painter, sculptor, and writer. As a painter, he belonged to the Sienese School. He was considered a visionary architectural theorist—in Nikolaus Pevsner's terms: "one of the most interesting later Quattrocento architects". As a military engineer, he executed architectural designs and sculptural projects and built almost seventy fortifications for the Federico da Montefeltro, Count of Urbino, building city walls and early examples of star-shaped fortifications.