The bicentenary of Trevithick's historic achievement was celebrated in 2004
Richard Trevithick paved the way for the railway age when he launched the world's first steam locomotive in Merthyr Tydfil on 21 February 1804.
Born in Cornwall in 1771, he learnt his trade in the tin mines where his father worked with pumping engines.
A huge man able to throw a sledgehammer over an engine house, Trevithick was scorned for attempting the impossible.
But in creating the high pressure steam engine, his reputation as a brilliant inventor reached Merthyr Tydfil.
Era of innovation
Samuel Homfray, master of Penydarren ironworks, obtained a share in Trevithick's patent and asked him to build a stationary engine.
At that time, the late eighteenth century, horse-drawn railways were used to carry coal and iron from mines in the South Wales Valleys and other industrial centres.
But Trevithick recognised that a steam engine on wheels - a locomotive - would be more effective than horses at pulling heavy loads.
A replica of the Penydarren locomotive stands outside Cyfarthfa Castle
Rival ironmaster Richard Crawshay dismissed the idea as preposterous. But Homfray had faith in Trevithick and bet his rival 500 guineas - a fortune in those days - that the engine would successfully pull a ten ton load of iron along a nine-and-a-half mile stretch of tramroad from Penydarren to Abercynon.
On 21 February 1804 history was made when Trevithick's locomotive "Penydarren" completed the journey in four hours and five minutes.
In fact, the load was much heavier than planned, up to 25 tons including the weight of the engine itself, the wagons, and around 70 people perched on them.
Despite his pioneering work with locomotives, Trevithick soon returned to his original job building stationary steam engines for water pumping.
He had no interest in fame and fortune except as a means of funding further experiments, and left the development of the railways to others such as George Stephenson.
As a result, Trevithick died in 1833, a few days after his 62nd birthday in relative poverty at Dartford, Kent, and was carried to a pauper's grave by colleagues at an engineering works.
Many reminders of Trevithick's pioneering work can be seen today in Merthyr - you can walk along the tramroad, see Trevithick's Tunnel, and view a replica of his locomotive outside Cyfarthfa Castle.