Until now, archaeologists have agreed on the point of view that in one building, there has to be one unit of measure in order to avoid confusion. In fact, an important advantage results when architects deliberately deviate from this principle. An analysis of the measurements of buildings has shown that in some eight instances, two units were used, in directions perpendicular to one another. It turned out that during the period beginning with the Great Pyramid and lasting at least to the Renaissance, architects used a grid of equilateral triangles, in which the height follows a unit other than the sides.