In the early nineteenth century Merthyr Tydfil was the iron capital of the world. There were four iron works, they were:- Cyfarthfa, Plymouth, Dowlais and Penydarren. Each of the iron works was very successful but Cyfarthfa and Dowlais were the most successful.
One of the most famous iron masters who is still well known today in Merthyr, was Crawshay. Crawshay owned the Cyfarthfa iron works and his family came from Merthyr Tydfil's castle called Cyfarthfa Castle, where he and his family lived in luxury.