Merthyr Tydfil is the county town of the Merthyr Tydfil County Borough which has been one of the 22 unitary authorities in Wales since 1 April 1996 (though the area was actually originally granted county borough status in 1908) The county is located in the historic county of Glamorgan and takes its name from the Merthyr Tydfil town The County Borough consists of the northern part of the Taff Valley and the smaller neighbouring Taff Bargoed Valley. It borders the counties of Rhondda Cynon Taf and Caerphilly county borough A horrendously sad fact that I remember clearly was on October 21st, 1966 when a mining tip on a mountain slope above the village of Aberfan (5 miles south of Merthyr Tydfil) collapsed after a heavy rain and slid downhill as a slurry, killing 116 children and 28 adults as it engulfed Pantglas Junior School and other buildings. (https://en.wikipedia.org/wiki/Aberfan_disaster) [ https://en.wikipedia.org/wiki/Merthyr_Tydfil_County_Borough ]