Running in a horse-shoe shape, it passes small market towns such as Llanidloes and quiet villages including Abbeycwmhir and Llanfyllin, traversing central Mid Wales to Machynlleth near the Dyfi estuary and back again across Wales via Lake Vyrnwy and the valley of the River Vyrnwy to Welshpool, close to the English border.
In 1837, Francis Philips (1771–1850) J.P., D.L., of Bank Hall, Lancashire, purchased the Abbeycwmhir estate which had fallen into a state of disrepair.