In art historical terms, an arch is a semicircular construction of blocks of material, called voussoirs, which hold each other in place due to compression, and span an open space. This type of arch is known as a “true arch.” Other simple forms of arches include the corbelled arch, in which blocks of material are overlapped in order to span a similar opening. The “true arch” is stronger than a corbelled arch, especially when constructed out of stone. The pointed arch, rather than the round arch, provides superior support and was widely used in Gothic cathedrals.