Also known as the Roman arch, the Semicircular Arch forms a half circle and is a major feature of all Roman architecture. A strong structure, this arch is often found in bridges and aqueducts. It appears a simple arch to manufacture, as each voussoir is identical in taper to its neighbour.

semi·​arch. "+ : an arch having only one springer and terminating at its highest point : half arch.

The setting out of a semi-circular arch is simple. Half the span is the rise. ROUGH segmental arches are built of standard bricks and the mortar between each brick is wedge-shaped. These arches are normally executed in stock bricks because the arch is used internally as a relieving arch.

Semicircular arch is an arch with intrados (inner surface) shaped like a semicircle. This type of arch was adopted and very widely used by the Romans, thus becoming permanently associated with the Roman architecture.