Horseshoe arch

An arch whose curve continues below the horizontal line of its diameter, so that the opening at the bottom is narrower than the arch's full span. Also called the Moorish or keyhole arch, it was used prominently by the Umayyads of al-Andalus, often enclosed in a rectangular frame known as the alfiz. It defines the Moorish architecture of Andalusian and Maghrebi palaces now operating as heritage hotels.