Abstract: A wall base block includes opposed top and bottom faces, first and second side faces, and first and second end faces. The first end face is convex, and the second end face is concave and of generally the same curvature as the first end face so that the convex first end face of one base block can closely nest the concave second end face of an adjacent base block. The block includes alignment indicia to assist in aligning adjacent nested blocks in straight or other predetermined angular relationships. The base blocks can be used to make straight or curved bases for a wall.