After various ups and downs, only in 1651 did construction start on the present church, today called the third Desio Basilica. The design was made by the architect of the Milan Duomo, Camillo Ciniselli, while the works were carried out under the direction of master builder Pietro Pozzi.
This church, which took in Pope Pius XI when he was but a child, marks another stage of splendour for art. Entering this grandiose temple and raising one's eyes, the glory of Saints Siro and Materno is seen in the majestic cupola, which dominates the whole town centre. The "scale" type of slate covering, placed with artisan expertise, gives the cupola its plastic characteristic, as it rises majestically on the fulcrum of the religious construction.