In Gothic architecture, a unique combination of existing technologies established the emergence of a new building style. Those technologies were the ogival or pointed arch, the ribbed vault, and the flying buttress. The Gothic style, when applied to an ecclesiastical building, emphasizes verticality and light. This appearance was achieved by the development of certain architectural features, which together provided an engineering solution. The structural parts of the building ceased to be its solid walls, and became a stone skeleton comprising clustered columns, pointed ribbed vaults and flying buttresses. (See below: Light) A Gothic cathedral or abbey was, prior to the 20th century, generally the landmark building in its town, rising high above all the domestic structures and often surmounted by one or more towers and pinnacles and perhaps tall spires. These cathedrals were the skyscrapers of that day and would have, by far, been the largest buildings that Europeans would have ever seen.  Plan
Most Gothic churches, unless they are entitled chapels, are of the Latin cross (or "cruciform") plan, with a long nave making the body of the church, a transverse arm called the transept and, beyond it, an extension which may be called the choir, chancel or presbytery. There are several regional variations on this plan. The nave is generally flanked on either side by aisles, usually single, but sometimes double. The nave is generally considerably taller than the aisles, having clerestory windows which light the central space. Gothic churches of the Germanic tradition, like St. Stephen of Vienna, often have nave and aisles of similar height and are called Hallenkirche. In the South of France there is often a single wide nave and no aisles, as at Sainte-Marie in Saint-Bertrand-de-Comminges. In some churches with double aisles, like Notre Dame, Paris, the transept does not project beyond the aisles. In English cathedrals transepts tend to project boldly and there may be two of them, as at Salisbury Cathedral, though this is not the case with lesser churches. The eastern arm shows considerable diversity. In England it is generally long and may have two distinct sections, both choir and presbytery. It is often square ended or has a projecting Lady Chapel, dedicated to the Virgin Mary. In France the eastern end is often polygonal and surrounded by a walkway called an ambulatory and sometimes a ring of chapels called a "chevet". While German churches are often similar to those of France, in Italy, the eastern projection beyond the transept is usually just a shallow apsidal chapel containing the sanctuary, as at Florence Cathedral.  Structure: the pointed arch
Norman blind-arcading at Canterbury Cathedral.
One of the defining characteristics of Gothic architecture is the pointed or ogival arch. Arches of this type were used in the Near East in pre-Islamic as well as Islamic architecture before they were structurally employed in medieval architecture, and are thus thought to have been the inspiration for their use in France, as at Autun Cathedral, which is otherwise stylistically Romanesque. However, contrary to the diffusionist theory, it appears that there was simultaneously a structural evolution towards the pointed arch, for the purpose of vaulting spaces of irregular plan, or to bring transverse vaults to the same height as diagonal vaults. This latter occurs at Durham Cathedral in the nave aisles in 1093. Pointed arches also occur extensively in Romanesque decorative blind arcading, where semi-circular arches overlap each other in a simple decorative pattern, and the points are accidental to the design.  Functions
The Gothic vault, unlike the semi-circular vault of Roman and Romanesque buildings, can be used to roof rectangular and irregularly shaped plans such as trapezoids. The other structural advantage is that the...