The Conwy valley line - Lein Dyffryn Conwy
Blaenau Ffestiniog to Trawsfynydd - Page 1
(this section of track is currently disused)
I came across this article and it might appeal to Railway enthusiasts. There are some nice viaducts on this line including the one at Llan Ffestiniog. There is also a very impressive viaduct at Cwm Prysor on the disused railway track from Trawsfynydd to Bala
http://www.penmorfa.com/Conwy/seven.htm