Ynyscedwyn Ironworks is an industrial complex located in Ystradgynlais, near Swansea, Wales.

[1] Crane was the first ironmaster who successfully tried anthracite to a blast furnace in 1837.

[2] In 1837, London bankers, Charles Price and Joseph Marryat, invested in the Ynyscedwyn Ironworks.

[3] The remaining structures were built in 1872 to house a planned steel mill.

Although not completed, the site housed the Ynyscedwyn Tinplate Works.