Former Railway Viaduct, Allt An Fhionn, St Fillans

The former railway viaduct at Allt An Fhionn in St Fillans was constructed between 1902 and 1904 by engineers Crouch and Hogg for the St Fillans to Lochearnhead section of the Caledonian Railway. This concrete viaduct is a notable example of early 20th century concrete engineering and holds historical significance due to its connection with the introduction of the railway to Loch Earn. It is one of three similar viaducts and bridges in St Fillans.

The viaduct spans five arches over the Allt-An-Fhionn Burn and is approximately 80 meters long, featuring a curved design. It is built from channeled mass concrete and includes five segmental arches. The parapet is characterized by a string course and a projecting cope, with shallow refuges located above each pier in the south parapet. The materials used in its construction include concrete and cast iron for the rainwater goods.