Its construction, begun in 1508, was not completed until a century later. Its architecture contrasts with that of Todi’s historic center, which is medieval in character. The architectural design has been attributed, albeit with some reservations, to Donato Bramante, while certain was the intervention of some of the most distinguished architects of the time: Cola di Matteuccio da Caprarola, Ambrogio da Milano, Antonio da Sangallo the Younger, Jacopo Barozzi known as "Il Vignola" and Baldassarre Peruzzi. The temple, with a central plan and Greek cross, has three polygonal apses and a semicircular one; inside, twelve plaster statues depicting the twelve apostles rest in as many niches, while above the high altar is the ancient image of The Madonna and Child and the Marriage of St. Catherine of Alexandria. The image, believed to be miraculous, was originally within the walls of a small chapel that had fallen into disrepair over the centuries. A mason found it covered with dust and cobwebs and, after wiping the sweat from his forehead with the same handkerchief with which he had cleaned the fresco, was miraculously cured of a serious eye disease. An annual festival remains in memory of this event, which is celebrated on September 8 and ends with a beautiful and impressive fireworks display.