Merthyr Tydfil is the main town in Merthyr Tydfil County Borough, Wales, administered by Merthyr Tydfil County Borough Council. It is about 23 miles (37 km) north of Cardiff. Often called just Merthyr, it is said to be named after Tydfil, daughter of King Brychan of Brycheiniog, who according to legend was slain at Merthyr by pagans about 480 CE. Merthyr generally means "martyr" in modern Welsh, b…