(c. 1444-1514) Italian Renaissance architect and artist. Inspired by Classical designs and by the work of Leonardo da Vinci, he was employed by Pope Julius II in rebuilding part of the Vatican and St Peter's in Rome. The circular Tempietto of San Pietro in Montorio, Rome (commissioned 1502; built about 1510), is possibly his most important completed work. Though small in size, this circular collonaded building possesses much of the grandeur of ancient Roman buildings.