Mines in Merthyr Tydfil

For a few decades in the 19th century Merthyr Tydfil made more iron than anywhere else on earth, and the four great ironworks — Cyfarthfa, Dowlais, Penydarren and Plymouth — sank their own pits and levels to feed the furnaces. The coal outlasted the iron by a century, and the pits that dug it were among the gassiest and, for a time, the deadliest in Wales.

Record created: 24 August 2026 · Last researched: 24 August 2026