The patron saint of Dego is Saint Ambrose, celebrated on 7 December. The parish church dedicated to him, in the locality of Dego Villa, was rebuilt in 1810 on the site of an earlier pre-existing building.
The castle of Dego Alta was built in the 13th century by the Del Carretto family on a rise north of the town; several hypotheses exist regarding the origin of the place name, including a derivation from the Old German Der Got, literally «the God», or from the Latin degere, to stay or dwell. In the hamlet of Ca' Bulin stands the Charterhouse of the Trinity, a monastery of Carthusian nuns founded in 1994 and today one of only five female charterhouses existing in the world, designed according to the traditional Carthusian model with separate cells, cloister and church. Among the territory's other religious buildings are the church of San Rocco, also in Dego Villa and dating from the 17th century, and the parish church of the Annunziata, in Baroque style with exposed stonework, in the locality of Dego Alta.
