File:Ceiling, Notre Dame, Paris, ZM.JPG|Six-part rib vaults of ceiling of Notre-Dame Cathedral File:Voutes, nef, rosace ouest et grandes orgues de la cathédrale Notre-Dame d'Amiens, France - 20080125-02.jpg|Four-part rib vaults at Amiens Cathedral allowed greater height and larger windows File:Amiens Cathédrale Notre-dame arc-boutant sud-est 4.jpg|Flying buttresses of
Amiens Cathedral. Pinnacles atop the buttresses added decoration and additional weight to strengthen the building File:Saint Denis PM 086190 F.jpg|North portal of
Basilica of St Denis, with early
tympanum and columns made of elongated figures File:Amiens cathedral Tympanumt.JPG|Day of Judgement
Tympanum at
Amiens Cathedral File:Chartres - cathédrale, vitrail (24).jpg|
Rose window in
Chartres Cathedral The rib vault The Gothic style emerged from innovative use of existing technologies, particularly the
pointed arch and the
rib vault. The rib vault was known in the earlier
Romanesque period, but it was not widely or effectively used until the Gothic period. The crossed ribs of the vault carried the weight outwards and downwards, to clusters of supporting pillars and columns. The earlier rib vaults, used at
Sens Cathedral and
Notre-Dame Cathedral, had six compartments bordered by ribs and the crossing arch, which transferred the weight to alternating columns and pillars. A new innovation appeared during the High Gothic: the four-part rib vault, which was used in
Chartres Cathedral,
Amiens Cathedral and
Reims Cathedral. The ribs of this vault distributed the weight more equally to the four supporting pillars below and established a closer connection between the nave and the lower portions of the church walls, and between the arcades below and the windows above. This allowed for greater height and thinner walls and contributed to the strong impression of verticality given by the newer Cathedrals.
The flying buttress The second major innovation of the Gothic style was the
flying buttress, which was first used at
Notre-Dame Cathedral. This transferred the thrust of the weight of the roof outside the walls, where it was countered by the weight of the buttress. Heavy stone
pinnacles were added to the top of the buttresses, to precisely counterbalance the thrust from inside the walls. The buttress allowed a significant reduction in the thickness of the cathedral walls, and permitted the use of larger windows in the interior of the church. In churches such as
Sainte Chapelle, due to buttresses, the walls were made almost entirely of stained glass. The development of rib-vaults and buttresses brought gradual changes to the interior structure of cathedrals. Early Gothic cathedrals had the walls of the nave built in four levels: a gallery with columns on the ground level; then the
tribune, a gallery with windows; then the
triforium, a row of smaller windows; and finally the high windows, just below the vaults. During the High Gothic period, with the development of the four-part rib vault and the flying buttress, the tribune was eliminated at Chartres and other new cathedrals, allowing taller windows and arcades. By the 15th century, at Rouen Cathedral, the triforium also disappeared, and the walls between the traverses were filled with high windows.
The portal and tympanum Another innovative feature of the French Gothic cathedral was the design of the
portal or entry, which by long Christian tradition faced west. The
Basilica of St Denis had a triple portal, decorated with columns in the form of statues of apostles and saints around the doorways, and biblical scenes crowded with statuary over the doorways. This triple portal was adopted by all the major cathedrals. A
tympanum over the portal, crowded with sculptural figures illustrating a biblical story became a feature of Gothic cathedrals. Following the example of Amiens, the tympanum over the central portal traditionally depicted the
Last Judgement, the right portal showed the coronation of the Virgin Mary, and the left portal showed the lives of saints who were important in the diocese.
Stained glass and the rose window Large
stained glass windows and
rose windows were another defining feature of the Gothic style. Some Gothic windows, like those at Chartres, were cut into the stone walls. Other windows, such as those in the chapels of Notre-Dame and Reims, were in stone frames installed into the walls. The most common form was an oculus, a small round window with two lancets, or windows with pointed arches, just below it. The rose window was the most famous type of the Gothic style. They were placed in the
transepts and the portals to provide light to the nave. The largest rose windows were ten meters in diameter. They had a framework of stone armatures often in an ornate floral pattern, to help them resist the wind. Gothic windows were in a stone frame separate from the wall, not cut into the wall. The early windows were made of pieces of tinted glass, touched up with
grisaille painting, and held in place by pieces of lead that outlined the figures. As the windows grew larger, more intense colors were used. After 1260, the colors became lighter, and the combination of grisaille and pale shades of yellow became more common.
Chartres Cathedral and
Le Mans Cathedral have some of the finest surviving original windows. ==Sculpture and symbolism - the "Book for the Poor"==