Er iddo ddisgwl fel adfail castell o’r Canol Oesoedd adeiladwyd Castell Graig, fel y’i gelwir, rhwng 1768-1775 gan John Morris i gartrefu rhai o’i lowyr a’u teuluodd. Dywedir y bu gan yr adeilad bedwar llawr a 24 o fflatiau. Erbyn 1880 roedd e wedi mynd a’i ben iddo.
Despite having the appearance of a medieval fortification, Morris Castle or Castle Graig, was built between 1768-1775 by John Morris to house some of his colliers and their families. The building consisted of four floors and a total of 24 compartments. It had become ruinous by 1880.