The Merthyr ironmaster William Crawshay II (1788-1867) had this neo-medieval "castle" built as his family seat. It was designed by the English architect Robert Lugar (1773-1855), built by local people out of local stone, and completed in 1825.

Six years before the Merthyr Uprising, Crawshay could look across the valley from his front lawn and see his employees' homes. 

Less than 100 years after its completion, in 1889, the castle was abandoned. The Crawshay family sold it to the city of Merthyr. in 1909 is was opened as a museum. Today its gardens are accessible to the public for free and the museum tells,  among other stories, the story of the Merthyr Uprising.