Merthyr Tydfil

Merthyr Tydfil county borough sits in the Taff valley in south Wales. The town grew around coal and iron industries in the 18th–19th centuries; sites include Cyfarthfa Ironworks and Dowlais. Cyfarthfa Castle, an ironmaster's mansion, now houses the Cyfarthfa Museum and Park. In 1804 Richard Trevithick ran his high‑pressure steam locomotive at the Penydarren Ironworks tramroad, one of the first steam locomotives to haul a load on rails; that trial took place along routes now within the borough. The River Taff runs through the town centre and across steep valley sides.
The council area extends from the urban centre into upland moor and reservoir country at the edge of the Brecon Beacons National Park. Reservoirs such as Pontsticill and the Taff Fechan catchments supply water and are starting points for hill walks that rise from valley floors to ridge lines. Villages and former colliery settlements, including Dowlais, Troedyrhiw and Treharris, sit on valley slopes linked by road and rail corridors following river lines. Local conservation work records the industrial archaeology of furnaces, tramroads and canal remains.