The church is located just outside the walls of the town and its construction dates back to 1281 but it was abandoned shortly after. Then from 1350 the church and monastery were managed by the congregation of the Servants of Mary who expanded the building.
According to an ancient legend, its name derives from the fact that in 1446 some children had seen the Madonna in this place and shouted “It is the truth, it is the truth!”.
From this moment a period of great splendour began with believers who contributed to its decorations like the Mazzatosta family who built one of the most beautiful medieval chapels frescoed by Lorenzo da Viterbo. The chapel has a vaulted roof and the frescoes in the sails represent the four evangelists, each flanked by a prophet and a scholar of the church. On the sides of the chapel you can admire the history of the Madonna, from the Annunciation to the Marriage of the Virgin set in medieval Viterbo.
The chapel has a majolica floor and a grille originating from the fifteenth century that was restored after the second world war.
Its location outside the walls has made it a centre of passage for many foreign communities such as Germans, Corsicans and Slavs and a reference point for guilds such as stone masters, weavers, wool masters and masons.
After the Unification of Italy, this church was nationalized and became a gym until 1912 when it became a civic museum. The bombings of the Second World War greatly damaged it and with its reconstruction the museum was moved to the nearby convent and the church reverted to religious worship.
The external façade in simple peperino stone has the shape of a hut with a central sixteenth-century door, framed and decorated with two small statues of the Madonna and an Announcing Angel, and a circular window above the door.
The interior has a single nave and a Latin cross plan and the lateral parts are the splendid chapel of San Sebastiano with precious frescoes such as a Madonna with Child from 1591. The other wing houses a superb Pinchi reed organ from 1986 with 31 registers on three manuals and pedal.
The nearby convent with its cloister now houses the Civic Museum.