Public footpath along the bypass

One of my favourite walks in Newtown, starts in the mochre by castell-y-dail through blue bell woods, under the bypass through a tunnel and then a footpath that runs parallel with the bypass, stunning views of the country valley and of Newtown, then to step-a-side road where you join the next half of the path that ends over the bridge by the caravan park, quite hilly so it certainly gets the blood pumping