Editing Clerestory (section)

==History==
[[File:Monreale.jpg|thumb|The walls of the clerestory of the [[Basilica#Christian adoption of the basilica form|basilica-shaped]] [[Monreale Cathedral|Cathedral of Monreale]], [[Italy]], covered with [[mosaic]]s]]

===Ancient world===
Clerestories appear to originate in [[Egyptian temple]]s, where the lighting of the hall of columns was obtained over the stone roofs of the adjoining aisles, through gaps left in the vertical slabs of stone. They appeared in Egypt at least as early as the [[Amarna Period]].<ref>Gwendolyn Leick and Francis J. Kirk, ''A Dictionary of Ancient Near Eastern Architecture'', 1988, Routledge, 261 pages {{ISBN|0-415-00240-0}}</ref> [[Minoan palaces]] in [[Crete]] such as [[Knossos]]  employed  [[lightwell]]s in addition to clerestories.<ref>C. Michael Hogan, [http://www.themodernantiquarian.com/site/10854/knossos.html#fieldnotes ''Knossos fieldnotes'', Modern Antiquarian (2007)]</ref>

According to the [[Hebrew Bible]], [[Solomon's Temple]] featured clerestory windows made possible by the use of a tall, angled roof and a central {{linktext|ridgepole}}.<ref name="Palmer2008">{{cite book|last=Palmer|first=Allison Lee|title=Historical Dictionary of Architecture|url=https://books.google.com/books?id=FHR9sHRfQ_0C&pg=PA267|access-date=2014-06-15|date=2008-09-11|publisher=Scarecrow Press|isbn=978-0-8108-6283-8|page=267}}</ref>

The clerestory was used in the [[Hellenistic art#Architecture|Hellenistic architecture]] of [[classical antiquity]]. The Romans applied clerestories to [[basilica]]s of justice and to the basilica-like [[thermae]] and palaces.

===Early Christian and Byzantine basilicas===
[[Early Christianity|Early Christian]] churches and some Byzantine churches, particularly in Italy, are based closely on the Roman basilica, and maintained the form of a central [[nave]] flanked by lower aisles on each side. The nave and aisles are separated by columns or piers, above which rises a wall pierced by clerestory windows.
[[File:malmesbury.abbey.clerestory.arp.jpg|thumb|upright|[[Malmesbury Abbey]], [[Wiltshire]], [[England]]. The nave wall is divided into three stages: the upper stage with windows is the clerestory, beneath it is the triforium, and the lowest stage is the arcade.]]

===Romanesque period===
During the [[Romanesque architecture|Romanesque]] period, many churches of the basilica form were constructed all over Europe. Many of these churches have wooden roofs with clerestories below them. Some Romanesque churches have [[barrel-vaulted]] ceilings with no clerestory. The development of the [[groin vault]] and [[ribbed vault]] made possible the insertion of clerestory windows.

Initially the nave of a large aisled and clerestoried church was of two levels: [[Arcade (architecture)|arcade]] and clerestory. During the Romanesque period, a third level was inserted between them, a gallery called the "[[triforium]]". The triforium generally opens into space beneath the sloping roof of the aisle. This became a standard feature of later Romanesque and Gothic large abbey and cathedral churches. Sometimes another gallery set into the wall space above the triforium and below the clerestory. This feature is found in some late Romanesque and early Gothic buildings in France.

The oldest glass clerestory windows still in place are from the late eleventh century, found in [[Augsburg Cathedral]] in [[Bavaria]], Germany.

===Gothic period===
[[File:Cathedrale d'Amiens - Grandes verrieres et voutes de la nef.jpg|thumb|220px|left|upright|The clerestory of [[Amiens Cathedral]] in northern France]]
In smaller churches, clerestory windows may be [[trefoil]]s or [[quatrefoil]]s. In some Italian churches they are [[Rose Window#Oculi|ocular]]. In most large churches, they are an important feature, both for beauty and for utility. The [[ribbed vault]]ing and [[flying buttress]]es of Gothic architecture concentrated the weight and thrust of the roof, freeing wall-space for larger clerestory [[Fenestration (architecture)|fenestration]]. Generally, in Gothic masterpieces, the clerestory is divided into [[bay (architecture)|bays]] by the vaulting shafts that continue the same tall columns that form the arcade separating the aisles from the nave.

The tendency from the early Romanesque period to the late Gothic period was for the clerestory level to become progressively taller and the size of the windows to get proportionally larger in relation to wall surface, emerging in works such as the Gothic architecture of [[Amiens Cathedral]] or [[Westminster Abbey]], where their clerestories account for nearly a third of the height of the interior.<ref name="Simpson1922">{{cite book|last=Simpson|first=Frederick Moore|title=History of Architectural Development|url=https://books.google.com/books?id=8MFCAAAAYAAJ&pg=PA273|year=1922|publisher=Longmans, Green, and Company|page=273}}</ref>