The A470 is a trunk road in Wales. It is the country's longest road at 186 miles (299 km) and links the capital Cardiff on the south coast to Llandudno on the north coast. While previously one had to navigate the narrow roads of Llanidloes and Dolgellau, both these market towns are now bypassed due to extensive road modernisation. The 26 miles (42 km) from Cardiff Bay to Merthyr Tydfil are mainly dual carriageway, but most of the route from north of Merthyr to Llandudno is single carriageway.

Llanidloes is a town and community on the A470 and B4518 roads in Powys, within the historic county boundaries of Montgomeryshire, Wales. The population in 2011 was 2,929, of whom 15% could speak Welsh. It is the third largest settlement in Montgomeryshire, after Newtown and Welshpool.