Carnon viaduct carries the railway from Truro to Falmouth (now branded the 'Maritime Line') over the valley of the Carnon River in west Cornwall, United Kingdom. The viaduct is situated half-a-mile (800 metres) northeast of Perranwell station which is five miles (8 km) from the line's terminus at Falmouth and three miles (5 km) from its junction with the Cornish main line at Truro.