The patron saint of Cologno Monzese is Saint Ambrose, celebrated on 7 December. From the 11th century the municipal territory was subject to the jurisdiction of the monastery of Sant'Ambrogio in Milan: one of the town's churches, of medieval origin, was inhabited by the same monastery's Cistercian monks from the 10th century until around the 18th, and still today preserves 15th-century frescoes, though it is now deconsecrated, with religious services moved to the modern church of Santi Marco e Gregorio, adjacent to the old building. In the nave of another town church stand 18th-century frescoes depicting the four evangelists and the Fathers of the Church, including Ambrose himself, alongside Gregory, Jerome and Augustine.
The territory, simply called Cologno before 1862, became part of the Corte di Monza during the early Middle Ages, an ancient clerical organisation subject to the archdiocese of Milan: from this affiliation comes the adjective «Monzese» that still distinguishes the municipality's name today. On 9 December 1866 a royal decree merged into it the settlements of Malnido, today San Maurizio al Lambro, and Bettolino Freddo, previously belonging to the municipality of Moncucco. Cologno Monzese is today conurbated with Milan and is known above all as the seat of Mediaset's main production centre, recognisable by its tower, located in the former studios where the famous Caroselli advertisements were once filmed.
