Four-centred arch

A four-centred arch, also known as a depressed arch or Tudor arch, is a low, wide type of arch with a pointed apex. It is much wider than its height and gives the visual effect of having been flattened under pressure. Its structure is achieved by drafting two arcs which rise steeply from each springing point on a small radius, and then turning into two arches with a wide radius and much lower springing point.