The A458 is a route on the UK highway network that runs from Mallwyd, near Machynlleth, in Wales, merging with the A456 Hagley Road and the Quinton Expressway on the outskirts of Birmingham, in Englan

Mallwyd is a small village at the most southern end of Gwynedd, Wales, in the Mawddwy community, in the valley of the River Dyfi. It lies on the A470 approximately halfway between Dolgellau and Machyn