|Location Map ( geo)|
|Distance:||4.7 miles (7.6 km)|
|Met:||A487, B4391, A496|
|Former Number(s):||B4408, B4391|
|Now part of:||A470|
|Route outline (key)|
A4108 was the number given to the road running from the A487 north of Trawsfynydd towards Blaenau Ffestiniog in North Wales, after it was upgraded from B4408 around 1947, and subsequently trunked. It eventually became an extension of the A470 in order to create a north–south cross country route through Wales.
Before being changed to B4408 sometime before 1932 in connection with the extension of the A496 to Blaenau Ffestiniog, the section of the route north of Llan Ffestiniog had been a part of the original B4407 from Llan Ffestiniog to Conwy; the road to the south was originally unclassified.