Rundbogens

Rundbogens are round arches used in architecture to span openings. They are semicircular arches formed by wedge-shaped stones, or voussoirs, around a central keystone. The arch distributes loads through compression to the supports at each end, enabling openings to be wider than in other construction methods without sacrificing stability. In architectural terminology, Rundbogens are distinguished from pointed, ogee, or horseshoe arches by their circular profile.

Historically, the round arch has ancient roots in the Mediterranean and Near Eastern building traditions, but it was the Romans who widely popularized and developed its structural use. Roman engineers employed Rundbogens in aqueducts, bridges, triumphal arches, and many masonry buildings, demonstrating the efficiency of arch-based construction. In medieval Europe, the semicircular arch remained central to Romanesque architecture, appearing in doorways, arcades, vaults, and windows. The form continued to influence later architectural styles, although it often yielded to the taller, more slender pointed arch in Gothic design.

Variants and usage include segmental rundbogen, a shallower arc used for doors and openings where a flatter profile is desired, and horseshoe arches seen in Islamic and Moorish architecture. Materials commonly used for Rundbogens include stone, brick, and concrete, with voussoirs cut to fit the desired radius. Today, round arches continue to appear in neoclassical and revival styles, in window and doorway designs, and in infrastructure such as bridges and vaults where a robust, compression-based system is advantageous.