Oratorio della Santissima Trinità, Medieval church in Momo, Italy.

The Oratorio della Santissima Trinità is a small rustic chapel with a pale plastered facade, a steep dark tiled gable roof and a wide arched opening framed by faded red painted decoration. Inside the arch stands a stone altarpiece with carved side columns and a central painted panel above a cloth-covered altar table; a black metal railing crosses the front. A 17th-century brick-and-river-stone hermit's house leans against the chapel.

The oratory was probably founded in the 11th century, when Cluniac expansion in northern Italy spread devotion to the Holy Trinity; it then served as a simple chapel for travellers on the old Via Francisca. The Romanesque apse and the base of the bell tower survive from that phase. Over the next two centuries it was enlarged and rebuilt as a church, and in 1594 Bishop Carlo Bascapè of Novara ordered the roof and facade restored.

The interior walls display frescoes from the late 15th and early 16th centuries, created by the Cagnola workshop from Novara. These painted scenes represent important examples of local artistic tradition during that period.

The oratory stands about two kilometres north of Momo on the west bank of regional road 229 toward Borgomanero, just off the old Via Francisca route. It sits outside the built-up area, so it is reached by car; the facade portico and the black railing at the entrance are the only shelter at the door.

Excavations during the 1982 restoration revealed archaeological finds showing that this site held sacred meaning during Celtic times. The discoveries suggest that the land had spiritual importance long before its Christian use.