Abstract: A wall is constructed from many wall units (31, 32, 33) that are fastened together, with each wall unit having moderate width and height dimensions. Each wall unit includes a pair of parallel and aligned face plates (40, 42) and a middle plate (44) sandwiched between the face plates. The middle plate is offset a distance (Df, Du) from alignment with the face plates, to leave a first unit (31) with a pair of tongues (60A, 62A) that project forwardly (F) and upwardly (U), and to leave a pair of grooves (64A, 66A) at the rear and bottom of the first unit. A frontward projecting tongue (60B) of a second unit (32) projects into a groove (64A) in the first unit, and an upwardly projecting tongue (62A) of the first unit projects upward into a groove (66C) at the bottom of a third unit (33).