Sbarramento Lodrino-Osogna, Military fortification complex in Riviera District, Switzerland

The Lodrino-Osogna fortification, known as the Lona Line, comprises 100 defensive structures on both sides of the Ticino River in the Riviera district. It includes anti-tank barriers crossing the valley floor, infantry bunkers, and artillery works in rock caverns. The artillery positions at Mairano and Mondascia housed 12-cm ring-tube cannons, later replaced by 10.5-cm howitzers.

Built between 1939 and 1942 by troops and private firms to plans of the 9th Division, the Lona line blocked the Ticino valley south of Biasca against landings on the Magadino plain and an advance through the Misox. In 1950–1960 it was reinforced near Iragna with prefabricated spherical bunkers and 8.1-cm fortress mortars, and in 1995, after the Cold War, it was declassified.

The name LONA is an acronym of LOdrino and OsogNA, the two villages at either end of the line, not a reference to a place called Lona. The same abbreviation names the Kampfgruppe Lona, the two-battalion unit raised to man the line. The artillery rock works Santa Pietà and San Martino take their names from the churches beside them.

The 100 structures lie on both banks of the Ticino between Lodrino, Osogna, Iragna and Biasca, south of Biasca; the artillery works at Mairano and Mondascia are the main group. Many bunkers stand on private or overgrown ground, so check access before entering and carry a torch. The command post A 8160 in Pollegio was disguised as a rustico.

The command post of the Lona position, A 8160, stood in Pollegio disguised as a rustic stone house and was only given up in 2003. The infantry bunker Grande at Lodrino's sports ground was hidden inside a dummy house. At Osogna a quarry was used after the war to build a rock work, A 8146, for two 8.1 cm fortress mortars about 30 m apart.