Merthyr Tramroad / Penydarren Ironworks

The Merthyr Tramroad (also called the Penydarren Tramroad) was a 9¾-mile horse-worked iron tramroad in South Wales, built by 1802 to connect the Penydarren Ironworks at Merthyr Tydfil with the Glamorganshire Canal at Abercynon. The line was a normal industrial tramroad of its day; it became famous as the venue for the demonstration on 21 February 1804 of the Penydarren locomotive, designed by Richard Trevithick for ironmaster Samuel Homfray, which on that day hauled 10 tons of iron, 70 men and five wagons over the route. This was the world's first known journey by a steam locomotive on rails.

Trevithick's engine proved too heavy for the cast-iron tramroad rails, which broke under it, and after a few further trips it was relegated to stationary blowing-engine duty at the ironworks. Despite the partial commercial failure of the experiment, the demonstration is a foundational moment in railway history. The site is commemorated by a stretch of the Taff Trail and by an exhibition at Cyfarthfa Castle Museum in Merthyr.