Abstract: A building corner arrangement for the outer wall of homes and other buildings that are formed from prefabricated panels made from concrete or other cementitious materials, which panels are of the type in which the panel end walls at each corner of the building outer wall are formed to define an angle that lies in the range of from about 0 to about 90 degrees, relative to the panel outside and inside wall surfaces defined by the panel, that results in the formation of, when two such panels are placed in the usual right angle relation to define a building outer wall corner, a groove or opening that, at the building corner in question, extends the height of such adjacent panels, which corner arrangement involves concrete or other cementitious material filling the indicated groove or opening, and shaped exteriorly of same to define a cornerstone-like configuration that may be similar to that found in the more expensive French Provincial style home, and including a method and mold for making the indicated building