No, there is no wall (as far as we know), but there is a theory that there is nothing outside of the universe, that space expands to hold the universe. If this theory is correct, there is someplace that there is no space at all. Seems like someone recently told me that there was nothing outside of the material of the big bang, that that was all of existance as space expanded for the big bang. Wonder who told me that. If the universe is actually finite physically, then there is an edge to it. if its infinite, then there is no edge. There is nothing mathematical about that.

the more man learns, the more he realises, he really does not know anything.