The Sanctuary of St. Mary of the Peace of Massa Martana was built between 8 March 1521 and 1589 along the route of the ancient Via Flaminia. the church conserves a fresco, a time within a small votive shrine, depicting the Our Lady of the Milk between the Ss. John the Baptist and Giacomo, called the sacred image of the Virgin Nursing the Child between John the Baptist and Saint James, by the painter Bartolomeo da Miranda, dating back to the mid 1400s and the school of the late gothic style. From the very moment of his building was entrusted to the Franciscan Fathers of the Third Order Regular of Saint Francis, already present in the territory and already resident in the nearby convent of Sant’Antonio di Busseto.
The church has an octagonal plan, inside is a complex structure designed in 1600 by the painter Andrea Polinori of Todi. In 1630 ended the work of Cappella Maggiore, for which was opened a side of the octagon that form the plan of the Church, and the choir. Among the numerous works of art preserved inside the church are the canvases of the painter Palminio Alvi (San Carlo Borromeo in adoration of the Crucifix of 1612, on the back of the altar, in front of the choir; San Francesco that delivery of the waist to the Third Order of 1613, in the second right altar), a San Francesco in prayer in front of a skull attributed to Pietro Paolo Sensini and a Virgin at prayer style by Barbiani Andrea.
The dome which replaced a roof spiovento and that in 1623 was in turn replaced by a lantern, decorated with frescoes arranged for concentric bands extending from the bottom upwards and illustrate the stories of the Old and New Testament, from the Creation of Adam to Christ the judge, by Giovanni Antonio Polinori realized between 1647 and 1649. Complete the decoration of the figures of the apostles, some saints and, higher up, a large crowd of angel musicians, while, from the top of the dome, seem to overlook the cherubim and seraphim. The figures of considerable plastic projection, are represented with great variety of postures, gestures and expressions and the same chromatic range, recovered in its original tones from a recent restoration, is highly sought after and lively. Of great charm is also the effect of spatial illusionism with architectural scenes and songs of the landscape that seem truly overcome artistically the boundaries imposed by the dome.