The Taff Vale Railway (TVR) was a standard gauge railway in South Wales, built by the Taff Vale Railway Company to serve the iron and coal industries around Merthyr Tydfil and to connect them with docks in Cardiff. It was opened in stages in 1840 and 1841.

Merthyr Tydfil is the main town in Merthyr Tydfil County Borough, Wales, administered by Merthyr Tydfil County Borough Council. It is about 23 miles (37 km) north of Cardiff. Often called just Merthyr, it is said to be named after Tydfil, daughter of King Brychan of Brycheiniog, who according to legend was slain at Merthyr by pagans about 480 CE. Merthyr generally means "martyr" in modern Welsh, but here closer to the Latin martyrium: a place of worship built over a martyr's relics. Similar place names in south Wales are Merthyr Cynog, Merthyr Dyfan and Merthyr Mawr.