The Horse Shoe Arch - Visigothic versus Islamic

 

Islamic architecture improved the Visigothic horseshoe arch in scale, geometry, structural use, decoration, repetition, and international spread.

The arch became more rounded and more visually refined

Visigothic horseshoe arches were often simple, thick, and relatively plain. In al-Andalus, the arch became more mathematically controlled and visually elegant. 

The “Moorish” horseshoe arch developed into a more circular and sophisticated form than the Visigothic version, often turning inward more strongly before reaching the imposts. (Wikipedia)
In simple terms: Visigothic was functional, heavy, local church form.

Whereas the Islamic Andalusi arch was more circular, more rhythmic, more decorative, and more monumental.

It was monumentalized at Córdoba 
The Great Mosque of Córdoba transformed the horseshoe arch from a local architectural feature into a grand imperial-religious system. 

Its prayer hall used repeated bays of double arches: lower horseshoe arches acting as structural ties, and upper semicircular arches supporting the roof. 

The arches used alternating red brick and white stone voussoirs, creating the famous striped visual rhythm. (Córdoba Mosque)

This was a major improvement because the arch was no longer just a doorway or small church divider. It became the organizing system for a vast hypostyle mosque interior.

Islamic builders added the alfiz
One of the most important Andalusi improvements was the alfiz: a rectangular frame surrounding the arch. This sharpened the visual outline of the horseshoe shape and made it more architectural and decorative. Sources specifically note that Umayyad builders in al-Andalus often enclosed horseshoe arches in an alfiz to emphasize their shape. (Wikipedia)

This became a signature of Andalusi and later Maghrebi architecture.

It became part of a color system
At Córdoba, Islamic builders used alternating red-and-white voussoirs, usually brick and stone, to turn the arch into a strong visual pattern. 

This made the arch both structural and decorative. (Wikipedia)

The Visigothic arch was usually more austere. Islamic Córdoba turned the arch into a rhythmic, almost textile-like architectural surface.

It was multiplied into a “forest of arches”
The Islamic improvement was not just the shape of one arch, but the repetition of hundreds of arches into a unified space.

 In Córdoba, rows of horseshoe arches created a vast interior rhythm. This turned the arch into a spatial experience, rather than just a structural opening.

That is a major difference: Visigothic churches used horseshoe arches, but Islamic Córdoba made them into an immersive architectural language.

It was combined with other arch types
Islamic architecture did not keep the horseshoe arch isolated. It combined it with:
pointed arches, lobed arches, multi-foil arches, interlacing arches, double-tiered arcades, and ribbed domes.
This made the horseshoe arch part of a much richer architectural grammar. 

The Córdoba mosque, especially its later expansions, shows horseshoe arches alongside intersecting and lobed forms, while later Andalusi-Maghrebi architecture developed these combinations further.

It was given elite decorative treatment
In the Córdoba mihrab, the horseshoe arch was framed and decorated with gold, glass mosaics, floral motifs, and epigraphic ornament. 

One source describes the mihrab horseshoe arch as framed by an alfiz decorated with gold and glass, with Byzantine artisans brought from Constantinople for the work. (Medina Azahara)
So the arch became more than a structural form. It became a sacred focal point.

It spread across the Islamic West
The Visigothic horseshoe arch was mainly a regional Iberian feature. Under Islamic rule, especially through Córdoba, it spread across al-Andalus and the Maghreb. 

The Córdoban style was adopted by later Muslim dynasties, taifas, and North African architecture. (Wikipedia)
In the above sense, Islamic architecture  did not just “borrow” the horseshoe arch. It made it more versatile and became a source of transmitting it beyond just the Iberian Peninsula. 

To summarize - 

The horseshoe arch existed in Visigothic Iberia before Islam, but Islamic architects in al-Andalus transformed it from a regional early-medieval form into a monumental, systematic, and highly decorative architectural language.

 At Córdoba, it was refined into a more circular form, multiplied across a vast hypostyle hall, combined with double-tiered arcades, striped red-and-white voussoirs, alfiz frames, mihrab ornament, lobed forms, and later ribbed/intersecting arches. 

Through al-Andalus and the Maghreb, Islamic architecture made the horseshoe arch one of the defining forms of western Islamic architecture.