In 122AD the Roman's occupying Britain began building what we now call Hadrian's Wall - probably to hold back the onslaught of those barbaric hordes from further north in what is now Scotland, and to ensure stability of the empire. Good portions of this wall, which is now in Northern England are entact. It is a UNESCO world heritage site.
Walking the whole length of the wall is an 84 mile hike. People typically walk it in the summer, and it is the most walked trail in Northern England. I think I'd like to walk it off-season personally.
I walked the Wye Valley in Wales/England slightly off-season, and we met only a few walkers along the path. Now that is my idea of a walking tour.
I would prefer to camp along the way, but a wall walker could stop in more luscious accommodations - I suppose (from B&Bs to Hotels to a Castle!)