Arch

A curved structure that carries load in compression toward supports at both ends.

Traditional masonry vocabulary includes voussoirs and keystones. Forms include semicircular, pointed, horseshoe, and elliptical arches used in bridges, openings, and arcades.

Modern steel and concrete arches combine compression with tension or prestress for thinner and longer spans. Understanding the load path matters more than the curve alone.

Roman aqueducts, city gates, and modern arch bridges form a continuous lineage. The flyer of a flying buttress is essentially an arch.