The oratory of Sant'Ambrogio is located in Segno, a hamlet of Cavagnago, and is a late Romanesque building, perhaps from the thirteenth century, extended westwards in subsequent centuries. The isolated bell tower is quadrangular, in open masonry, with mullioned windows. Outside the building on the south wall are visible some frescoes depicting two saints (perhaps Peter and Anthony abbot) and a Crucifixion with the Virgin, St. John the Evangelist and two angels, dating from the fifteenth century.
The interior has a single nave with a semicircular apse. In the apse cup Majestas Domini and the symbols of the Evangelists; in the lower register, the theory of Saints with a Crucifixion in the centre partly destroyed by the reopening of the single lancet window (1931). The late Gothic frescoes are attributed to painters from the circle of the Seregnesi and represent Saint Lawrence, Saint Catherine of Alexandria and Saint Margaret, Saint Michael the Archangel (15th century). On the walls, S. Ambrogio and Madonna Enthroned, attributed to Nicolao da Seregno, with traces of previous paintings, and a fresco, partly rebuilt, dating from the early '400 and depicting a Madonna Enthroned between Saints Anthony Abbot and Magdalene.
- Closed all year round.
- Key at La Faura Restaurant (next to the church).
- 4th Sunday in July Patronal Feast of St. Anne.