The oldest place of worship in Stimigliano was built by the noble Galla, daughter of Aurelio Simmaco who was slain in 525 by order of the Gothic king Theodoric. The noble woman, widowed, consecrated herself to God for whose glory she erected numerous churches in the Viterbo area and in the overlooking Sabina.
In the church of S.Valentino, in addition to the high altar dedicated to the saint which is depicted on a canvas, there were also two chapels of lay law: the chapel of S.Caterina erected by Giovanni Maria Bartolazio in 1582, with altar and paintings and that dedicated to the Annunciation of the Blessed Virgin Mary, erected by Valentino Branca in 1599.
It should be remembered that among the various commitments that weighed on the church, there was also the jussepeliendi with the introduction of new rules for burial outside inhabited centers. During the pastoral visit of 1779, Cardinal Corsini had noticed the serious deterioration of the ancient church, so he ordered the immediate restoration of the building, including the adjoining house that had been transformed into a hermitage. The further works of 1980 allowed to deepen other technical-artistic aspects.
The entrance portal and the door of the sacristy have been reduced; the presbytery was connected to the floor of the church by three steps. Evidently the whole floor had been raised by about a meter to increase the capacity of the funeral deposits. Decorations dating back to the second half of the 16th century have become visible on the apse vault. Also from documents relating to the pastoral visit of Cardinal Corsini, it appears that the tomb of the children was located in the sacristy of the church.
Outside, on the east side, there was instead the tomb of the drowned, that is, of the suicides. The church of S.Valentino, regularly officiated until 1940, was reopened for worship in 1981 due to the active commitment of the parish priest Rev. Don Attilio Attili.