Merthyr Tydfil sits at the head of the Taff Valley. It is a place where industrial grit meets mountain air. My top tip is to visit the grounds of Cyfarthfa Castle. You can walk the paths and see the lake for free. This is a prime choice for a low cost day out. The stone arches of the Cefn Coed Viaduct tower over the river. You can ride the steam train from Pant to see the hills. The Taff Trail offers a flat path for a long walk. Red kites fly high above the old ironworks. The town has deep roots in the story of coal. It is a smart spot for a trip.