The theories that have been advanced concerning the Roman Wall in England and its attendant works have been so many, so divergent, and at times so rapid in their succession as almost to justify the favourite taunt of irresponsible criticism, that their sequence is a matter of fashion or caprice rather than of rational development. Such a criticism, whether directed against historical, scientific or philosophical thought, hardly merits refutation. The object of this essay is rather to tell a plain tale, the story of the process by which, in the three centuries that have elapsed since Camden took it up, the problem of the Wall has been attacked first in one way and then in another till finally, within the last generation, a complete solution seems to have come within the range of possibility.