The term Norman architecture is used to categorise styles of Romanesque architecture developed by the Normans in the various lands under their dominion or influence in the 11th and 12th centuries. In particular the term is traditionally used for English Romanesque architecture. The Normans introduced large numbers of castles and fortifications including Norman keeps, and at the same time monasteries, abbeys, churches and cathedrals, in a style characterised by the usual Romanesque rounded arches (particularly over windows and doorways) and especially massive proportions compared to other regional variations of the style. Origins These Romanesque styles originated in Normandy and became widespread in northwestern Europe, particularly in England, which contributed considerable development and where the largest number of examples survived. At about the same time, a Norman dynasty that ruled in Sicily produced a distinctive variation–incorporating Byzantine and Saracen influences–also known as Norman architecture (or alternatively Sicilian Romanesque). The term Norman may have originated with eighteenth-century antiquarians, but its usage in a sequence of styles has been attributed to Thomas Rickman in his 1817 work An Attempt to Discriminate the Styles of English Architecture from the Conquest to the Reformation. In this work he used the labels "Norman, Early English, Decorated, and Perpendicular". The more inclusive term romanesque was used of the Romance languages in English by 1715, and was applied to architecture of the eleventh and twelfth centuries from 1819. Although Edward the Confessor built the original Westminster Abbey in Romanesque style (now all replaced by later rebuildings), its construction predates the Norman Conquest: it is still believed to be the earliest major Romanesque building in England. No other significant remaining Romanesque architecture in Britain can clearly be shown to predate the Norman Conquest. However, historians believe that many surviving "Norman" elements in buildings–nearly all churches–may well in fact be Anglo-Saxon elements. Norman arch The Norman arch is a defining point of Norman architecture. Grand archways are designed to evoke feelings of awe and are very commonly seen as the entrance to large religious buildings such as cathedrals. Norman arches are semicircular in form. Early examples have plain, square edges; later ones are often enriched with the zig-zag and roll mouldings. The arches are supported on massive columns, generally plain and cylindrical, sometimes with spiral decoration; occasionally, square-section piers are found. Main doorways have a succession of receding semicircular arches, often decorated with mouldings, typically of chevron or zig-zag design;