53 and 73 respectively lower edge 33 includes channel 35 similarly lower edge 53 includes channel 55 and lower edge 73 includes channel 75 channels 35 55 75 are longitudinally aligned as best seen in fig1 channels 35 55 75 of the base row of blocks 15 receive guiding wall 86 of base alignment tool assembly 80 as shown in fig1 base alignment tool assembly 80 is a base tool for horizontally aligning the lowermost row of blocks 15 base alignment tool assembly 80 also permits a user to level the base when the footing or horizontal surface that is supporting assembly 80 has irregularities base alignment tool assembly 80 includes longitudinally extending sheet 82 with perpendicularly mounted guiding wall 86 guiding wall 86 includes through openings 86 u2032 at its longitudinal ends guiding wall 86 is cooperatively positioned to be inserted into channels 35 55 and 75 sheet 82 includes through threaded openings 81 in the preferred embodiment disposed along the entire length of sheet 82 and adjacent to the longitudinal edges of sheet 82 through openings 83 are also disposed along the entire length of sheet 82 through openings 84 are cooperatively disposed in vertical alignment with cavities 60 and 62 as best seen in fig1 b through openings 81 cooperatively and selectively receive screw members 85 or fastening similar members screw members 85 level base alignment tool assembly 80 when horizontal alignment is required additionally pin members 87 pass through openings 83 on individual.