The Treffry Viaduct is a historic dual-purpose railway viaduct and aqueduct located close to the village of Luxulyan, Cornwall in the United Kingdom. The viaduct crosses the Luxulyan Valley and is part of the Treffry Tramways. It forms an integral part of the Cornwall and West Devon Mining Landscape, a World Heritage Site. It is scheduled under the Ancient Monuments and Archaeological Areas Act 1979 and due to its poor condition is on Historic England's, Heritage at Risk Register.