The Cefn-coed Viaduct, Merthyr Tydfil.

The Cefn-coed Viaduct is the third-largest viaduct in Wales. This huge, curved structure once carried the Brecon and Merthyr Tydfil Junction Railway. Opened in 1868 consisting of 15 arches with a maximum height of 115ft. Th viaduct closed to use in 1968 and is now part of the Taff Trail