"If everything in my book is wrong, then the opposite may well be true." Weird.
We used to live near the "Old Stone Fort" in central Tennessee, which was once considered to have been built by the Welsh explorers. Now they say proto-Cherokees built it, but how one could tell is beyond me. A very interesting site.
Maybe the proto-Cherokee were the Welsh, huh?
Also, the materials used and the style is representitive of who built it.