Monte Osero, Mountain summit in Province of Piacenza, Italy.

Monte Osero is a 1,301-metre mountain on the watershed between the Perino and Nure valleys, on the border between the municipalities of Bettola and Farini in the Province of Piacenza. Its summit is a wide meadow with a single solitary tree, in whose branches sits a small shrine with a Madonna statuette. The slopes are covered with beech woods and reforested conifer stands, while the Perino side drops as a steep wooded wall to the valley floor.

Between 1 and 3 December 1944 the slopes between Monte Aserei and the Pia pass, including Monte Osero, were the setting of the Battle of Cerro, fought along the defensive line dividing the Nure valley from the Trebbia and Perino valleys. A civilian and a partisan were killed. The mountain had already been a site of clashes between partisans and German and Republican troops.

The summit holds a small shrine with a Madonna statuette, reflecting local religious customs and serving as a spiritual landmark for those who climb here. Visitors often leave small items or prayers at this spot, showing how meaningful the place remains for people in the region.

The summit is reached on foot from the hamlet of Montosero, in the municipality of Bettola. CAI trails cross the slopes and can also be ridden by mountain bike. Each May the GAEP organises a 33 km march from Passo del Cerro to Passo del Crociglia that passes over Monte Osero.

Wreckage of an American Douglas A-20 Havoc aircraft from World War II was discovered at the summit, evidence of the aerial combat that took place over this mountainous region. This crash site remains a tangible reminder of the wartime events that unfolded above the slopes.