The False Arch.
A 'false arch' is the name given to an opening formed by corbelling courses of stone from each side until they meet at a midpoint, where a capstone is then laid to complete the work. In this picture the big A 'arch' and a lot of the other openings are variations of false arches ( even the O opening in the R ). They are not true aches because they are not displacing the weight the same way a 'true' arch does.
The structural component of a false arch is dependent on the weaker tensile strength of stone. The courses of stones are merely inching over the opening, straddling it, rather than sending the force of the load in an arc around the opening, utilizing the material's stronger compressive strength .
