Horseshoe arch

The horseshoe arch (Arabic: قوس حدوة الحصان; Spanish: arco de herradura), also called the Moorish arch and the keyhole arch, is a type of arch in which the circular curve is continued below the horizontal line of its diameter, so that the opening at the bottom of the arch is narrower than the arch's full span. Evidence for the earliest uses of this form are found in Late Antique and Sasanian architecture, but it became emblematic of Islamic architecture, especially Moorish architecture. It also made later appearances in Moorish Revival and Art Nouveau styles. Horseshoe arches can take rounded, pointed or lobed form.