Architecture, the practice of building design andits resulting products; customary usage refersonly to those designs and structures that areculturally significant.
Architecture is tobuilding as literature is to the printed word.Vitruvius, a 1st-century BC Roman, wroteencyclopedically about architecture, and theEnglish poet Sir Henry Wotton was quoting him inhis charmingly phrased dictum: “Well building haththree conditions: Commoditie, Firmenes, andDelight.” More prosaically, one would say todaythat architecture must satisfy its intended uses,must be technically sound, and must conveyaesthetic meaning. But the best buildings areoften so well constructed that they outlast theiroriginal use. They then survive not only asbeautiful objects, but as documents of the historyof cultures, achievements in architecture thattestify to the nature of the society that producedthem. These achievements are never wholly the workof individuals. Architecture is a social art.Architectural form is inevitably influenced by thetechnologies applied, but building technology isconservative and knowledge about it is cumulative.
Precast concrete, for instance, has not renderedbrick obsolete.Although design and constructionhave become highly sophisticated and are oftencomputer directed, this complex apparatus rests onpreindustrial traditions inherited from millenniaduring which most structures were lived in by thepeople who erected them. The technical demands onbuilding remain the elemental ones-to excludeenemies, to circumvent gravity, and to avoiddiscomforts caused by an excess of heat or cold orby the intrusion of rain, wind, or vermin. This isno trivial assignment even with the best moderntechnology. The availability of suitable materialsfostered the crafts to exploit them and influencedthe shapes of buildings. Large areas of the worldwere once forested, and their inhabitantsdeveloped carpentry.
Although it has becomerelatively scarce, timber remains an importantbuilding material.Many kinds of stone lendthemselves to building. Stone and marble werechosen for important monuments because they areincombustible and can be expected to endure. Stoneis also a sculptural material; stone architecturewas often integral with stone sculpture. The useof stone has declined, however, because a numberof other materials are more amenable to industrialuse and assembly. Some regions lack both timberand stone; their peoples used the earth itself,tamping certain mixtures into walls or formingthem into bricks to be dried in the sun. Laterthey baked these substances in kilns, producing arange of bricks and tiles with greater durability.
Thus, early cultures used substances occurring intheir environment and invented the tools, skills,and technologies to exploit a variety ofmaterials, creating a legacy that continues toinform more industrialized methods.Building withstones or bricks is called masonry. The elementscohere through sheer gravity or the use of mortar,first composed of lime and sand. The Romans founda natural cement that, combined with inertsubstances, produced concrete. They usually facedthis with materials that would give a betterfinish.
In the early 19th century a trulywaterproof cement was developed, the keyingredient of modern concrete. In the 19th centuryalso, steel suddenly became abundant; rollingmills turned out shapes that could make structuralframes stronger than the traditional woodenframes.Moreover, steel rods could be positionedin wet concrete so as to greatly improve theversatility of that material, giving impetus earlyin the 20th century to new forms facilitated byreinforced concrete construction. The subsequentprofusion of aluminum and its anodized coatingsprovided cladding (surfacing) material that waslightweight and virtually maintenance free. Glasswas known in prehistory and is celebrated for itscontributions to Gothic architecture. Its qualityand availability have been enormously enhanced byindustrial processing, which has revolutionizedthe exploitation of natural light andtransparency. When masonry materials are stackedvertically, they are very stable; every part isundergoing compression. The real problem ofconstruction, however, is spanning.
Ways must befound to connect walls so as to provide a roof.The two basic approaches to spanning arepost-and-lintel construction and arch, vault, anddome construction. In post-and-lintelconstruction, lintels, or beams, are laidhorizontally across the tops of posts, or columns;additional horizontals span from beam to beam,forming decks that can become roofs or be occupiedas floors. In arch, vault, and dome construction,the spanning element is curved rather thanstraight. In the flat plane of a wall, arches maybe used in rows, supported by piers or columns toform an arcade; for roofs or ceilings, a sequenceof arches, one behind the other, may be used toform a half-cylinder (or barrel) vault; to spanlarge centralized spaces, an arch may be rotatedfrom its peak to form a hemispherical dome (seeArch and Vault; Dome). Post-and-lintel solutionscan be executed in various materials, but gravitysubjects the horizontal members to bending stress,in which parts of the member are in compressionwhile others are in tension.
Wood, steel, andreinforced concrete are efficient as beams,whereas masonry, because it lacks tensilecomponents, requires much greater bulk and weight.Vaulting permits spanning without subjectingmaterial to tension; thus, it can cover largeareas with masonry or concrete.Its outwardthrust, however, must be counteracted by abutment,or buttressing. Trussing is an importantstructural device used to achieve spans with lessweighty construction. Obviously, a frame composedof three end-connected members cannot change itsshape, even if its joints could act as hinges.Fortunately, however, the principle oftriangulation-attaching a horizontal tie beam tothe bottom ends of two peaked rafters-can beextended indefinitely. Spanning systems of almostany shape can be subdivided into triangles, thesides of which can be made of any appropriatematerial-wood, rolled steel, or tubing-andassembled using suitable end connections.
Eachseparate part is then subject only to eithercompressive or tensile stress. In the 18thcentury, mathematicians learned to apply theirscience to the behavior of structures, thus makingit possible to determine the amounts of thesestresses.This led to the development of spaceframes, which are simply trusses or other elementsarrayed three-dimensionally. Advances in the artof analyzing structural behavior resulted from thedemand in the 19th century for great civilengineering structures: dams, bridges, andtunnels. It is now possible to enclose space withsuspension structures-the obverse of vaulting, inthat materials are in tension-or pneumaticstructures, the skins of which are held in placeby air pressure. Sophisticated analysis isparticularly necessary in very tall structures,because wind loads and stresses that could beinduced by earthquakes then become more importantthan gravity.
Architecture must also take intoaccount the internal functional equipment ofmodern buildings. In recent decades, elaboratesystems for vertical transportation, the controlof temperature and humidity, forced ventilation,artificial lighting, sanitation, control of fire,and the distribution of electricity and otherservices have been developed.This has added tothe cost of construction and has increasedexpectations of comfort and convenience. In modernarchitectural terminology the word program denotesthe purposes for which buildings are constructed.
Certain broad purposes have always beendiscernible. The noblest works-temples, churches,mosques-celebrate the mysteries of religion andprovide assembly places where gods can bepropitiated or where the multitudes can beinstructed in interpretations of belief and canparticipate in symbolic rituals. Another importantpurpose has been to provide physical security:Many of the world’s most permanent structures werebuilt with defense in mind.
Related to defense isthe desire to create buildings that serve asstatus symbols. Kings and emperors insisted onpalaces proclaiming power and wealth.People ofprivilege have always been the best clients ofdesigners, artists, and artisans, and in theirprojects the best work of a given period is oftenrepresented. Today large corporations,governments, and universities play the role ofpatron in a less personal way. A proliferation ofbuilding types reflects the complexity of modernlife. More people live in mass housing and go towork in large office buildings; they spend theirincomes in large shopping centers, send theirchildren to many different kinds of schools, andwhen sick go to specialized hospitals and clinics.They linger in airports on the way to distanthotels and resorts.
Each class of facility hasaccumulated experiences that contribute to theexpertise needed by its designers. The attentionof clients, architects, and users is more and morefocused on the overall qualities manifested byaggregates of buildings and parts of cities asbeing more significant than individual structures.As the total building stock grows, conservingbuildings and adapting them for changes in usebecomes more important.See City Planning. Theaesthetic response to architecture is complex.
Itinvolves all the issues already discussed, as wellas other, more abstract qualities. An experienceof architectural space is personal andpsychological; it differs from that of sculptureor painting because the observer is in it. It isaffected by associations the observer may havewith the materials used and the way they have beenassembled, and by the lighting conditions.Structural logic may or may not have beendramatized. Elements such as windows, and theirscale and rhythm, affect the observer, as do theinterplay of geometrical form and the way space isarticulated.Movement through a sequence of spaceshas narrative force; no single point of view isadequately descriptive. The recurrence of thematicforms, appearing in varied guises and contexts,contributes to unity and createsfeelings-relaxation and protection or stimulationand awe.
Perhaps the key element is proportion-therelation of various dimensions to one another andtheir relation to human scale. During the mid-19thcentury, architecture became institutionalized asa profession requiring formal preparation andsubject to codes of performance. During thisperiod connoisseurship-full academic training inthe history of architecture and its aesthetics-wasthe designer’s most important qualification. Inevery Western country the cole des Beaux-Arts inParis was accepted as the model for architecturaleducation.
Architecture was easily separated fromengineering, which had pragmatic rather thanaesthetic goals. Yet today the profession deliversnot only aesthetic guidance but also a bewilderingarray of technical services requiring manyspecialized contributors. The architect strives tomaintain the position of generalist, one who cantake the long view while orchestrating theresolution of complex interrelated issues. For theconvenience of Western readers, the architectureof the ancient world, of the Orient, and of thepre-Columbian Americas may be divided into twogroups: indigenous architecture, or ways ofbuilding that appear to have developedindependently in isolated, local culturalconditions; and classical architecture, thesystems and building methods of Greece and Rome,which directly determined the course of Westernarchitecture. The oldest designed environmentsstable enough to have left traces date from thefirst development of cities. This region, thegreater part of modern Iraq, comprises the lowervalleys of the Tigris and Euphrates rivers.TheAssyrian city of Khorsabad, built of clay andbrick in the reign of Sargon II (reigned 722-705BC), was excavated as early as 1842, and much ofits general plan is known.
It became the basis forthe study of Mesopotamian architecture, becausethe far older cities of Babylon and Ur were notdiscovered and excavated until the late 19th and20th centuries. See Mesopotamian Art andArchitecture. Early Persianarchitecture-influenced by the Greeks, with whomthe Persians were at war in the 5th centuryBC-left the great royal compound of Persepolis(518-460 BC), created by Darius the Great, andseveral nearby rock-cut tombs, all north of Shrazin Iran. See Iranian Art and Architecture. Theurban culture of Egypt also developed very early.Its political history was more stable, however,with strong continuity in the development andconservation of tradition.
Also, granite,sandstone, and limestone were available inabundance. These circumstances, in a culturalsystem conferring enormous power on rulers andpriests, made possible the erection, over a longperiod, of the most awesome of the world’s ancientmonuments. Each Egyptian ruler was obsessed withconstructing a tomb for himself more impressiveand longer lasting than that of his predecessors.Before the 4th Dynasty (begins c.
2680 BC)Egyptian royal burial took the form of themastaba, an archetypal rectangular mass ofmasonry. This evolved into the stepped pyramid andfinally into the fully refined pyramid, of whichthe largest and best preserved are those of Khufu(built c. 2570 BC) and Khafre (circa 2530 BC) atGiza near Cairo.These immense monuments testifyto the pharaohs’ vast social control and also tothe fascination of their architects with abstract,perfect geometrical forms, a concern thatreappears frequently throughout history. Egyptiansbuilt temples to dignify the ritual observances ofthose in power and to exclude others. Thus, theywere built within walled enclosures, their greatcolumned halls (hypostyles) turning inward,visible from a distance only as a sheer mass ofmasonry.
A hierarchical linear sequence of spacesled to successively more privileged precincts. Inthis way was born the concept of the axis, whichin the Egyptian temples was greatly extended byavenues of sphinxes in order to intensify theclimactic experience of the approachingparticipants. The temples also introduce themonumental use of post-and-lintel construction instone, in which massive columns are closely spacedand bear deep lintels.The best-known Egyptiantemples are in the mid-Nile area in the vicinityof the old capital, Thebes. Here are found thegreat temples of Luxor, Karnak, and Deir al Bahri(15th-12th century BC) and Idfu (3rd century BC).
See Egyptian Art and Architecture; Temple. Hindutraditions are rich in visual symbols; the earlystone architecture of India was elaboratelycarved, more like sculpture than building,especially as the designers did not emphasizestructural systems and rarely faced the task ofenclosing large spaces. The Indian commemorativemonument takes the form of large hemisphericalmounds called stupas, like the one built from the3rd century BC to the 1st century AD, duringBuddhist ascendancy, at Sanchi, near Bhopal incentral India. In the early period of monasteryand temple building, shrines were sculpted out ofthe solid rock of cliffs. At sites such as Elloraand Ajanta, northeast of Bombay, are great seriesof these artificial caves carved over manycenturies.As the art of temple buildingdeveloped, construction by subtraction gave way tothe more conventional method of adding stones toform a structure, always, however, with moreconcern for sculptural mass than for enclosedvolume. Hindu temples are found throughout India,especially in the south and east, which were lessdominated by the Mughal rulers. Jainism, still avery successful cult, has its own temple traditionand continues to build on it.
See Indian Art andArchitecture. In Southeast Asia a Buddhist templeis called a wat. The most famous of these, andperhaps also the largest known, is Angkor Wat incentral Cambodia, built in the early 12th centuryunder the long-dominant Khmer dynasty.A richlysculptured stone complex, it rises 61 m (200 ft)and is approached by a ceremonial bridge 183 m(600 ft) long that spans the surrounding moat.Buddhist architectural traditions, sometimescoming via China, are strongly evident in Myanmar(formerly known as Burma), Thailand, Malaysia,Java, and Sri Lanka. The rich temples and shrinesof the Royal Palace compound in Bangkok are lessthan 200 years old, testifying to that culture’scontinuing vitality. The cultures of China andJapan have shared many features, but each has usedthem according to its national temperament.
Theresultant architectures are quite different fromeach other in both form and purpose. China has atraditional reverence toward ancestors; the stableand hierarchical life of the Chinese extendedfamily is proverbial. It is reflected in theformality of the Chinese house, built inrectangular form, preferably at the northern endof a walled courtyard entered from the south, withauxiliary elements disposed in a symmetricalfashion on either side of the north-south axis.This pattern was the point of departure for morelavish programs for mansions, monasteries,palaces, and, eventually, whole cities.
The cityof Beijing took form over a very long time, undervarious rulers. Two contiguous rectangles, theInner City and the newer Outer City, each embraceseveral square kilometers. The Inner City containsthe Imperial City, which in turn contains theForbidden City, which sheltered the imperial courtand the imperial family. The entire developmentadheres to symmetry along a strong north-southavenue-the apotheosis, on a grand urban scale, ofthe Chinese house. Stone, brick, tile, and timberare available in both China and Japan.
The mostcharacteristic architectural forms in bothcountries are based on timber framing.In China,the wooden post carried on its top an openworktimber structure, a kind of inverted pyramidformed of layers of horizontal beams connected andsupported by brackets and short posts to supportthe rafters and beams of a steep and heavy tileroof. The eaves extended well beyond column lineson cantilevers. The resulting archetype isrectangular in plan, usually one story high, witha prominent roof.
See Chinese Art andArchitecture. The Japanese house developeddifferently. The Japanese express a deep poeticresponse to nature, and their houses are moreconcerned with achieving a satisfying relationshipwith earth, water, rocks, and trees than withestablishing a social order.This approach isepitomized in the Katsura Detached Palace (1sthalf of the 17th century), designed and built by amaster of the tea ceremony. Its constructionsramble in a seemingly casual way, but in realityconstitute a carefully considered sequence alwaysintegrated with vistas to or from outdoorfeatures. Japan had already perfected timberprototypes early in its history. The Ise Shrine,on the coast southwest of Tokyo, dates from the5th or 6th century; it is scrupulously rebuiltevery 20 years.
Its principal building, within arectangular compound containing auxiliarystructures, is a timber treasure house elevated onwooden posts buried in the ground and crowned by amassive roof of thatch. Lacking both bracketingand trussing, the ridge is supported by a beam orridgepole held up by fat posts at the middle ofeach gabled end; the forked rafters, joining atopthe ridgepole, exert no outward thrust.This tinybut beautifully proportioned and crafted monumentis an excellent example of the understatedsubtlety of the art of Japan. See Japanese Art andArchitecture.
The nomadic North American tribesleft little permanent building, but the Pueblos ofSonora, Mexico, and of Arizona and New Mexico didbuild in stone and adobe. These cultures werealready in decline by AD 1300; a number ofimpressive cliff dwellings and other villagesremain as significant monuments. See NativeAmericans. The Spanish conquistador Hernn Cortsencountered the Aztecs in 1519 and within twoyears had destroyed their capital city,Tenochtitln, where Mexico City now stands.But hepassed over the nearby center of the olderTeotihuacn culture (100 BC-AD 700), which has nowbeen extensively restored and excavated.Teotihuacn contains two immense pyramids-of thesun and of the moon-that recall those of Egypt.They are arranged, along with other monuments andplazas, on a north-south axis at least 3 km (2 mi)in length, and the complex is embedded in what wasa vast city, laid out accurately in blocks.
MonteAlbn, near Oaxaca de Jurez, was the center of theZapotec culture that flourished about the sametime. Its imposing stone structures are set arounda spacious plaza created by leveling the top of amountain. The Mayan civilization had existed for2700 years when first confronted by the Spanish inthe 17th century, but its greatest buildingperiods fall within the 4th to the 11th century.The Maya occupied every part of the YucatnPeninsula, the principal sites, in roughly theorder of their development, being Copn (Honduras),Tikal (Guatemala), Palenque, Uxmal, Chichn Itz,and Tulum (Mexico). The important ceremonialmonuments found in these centers are of stone;although the enclosure of space has more emphasisthan in other pre-Columbian cultures, the Mayansnever mastered the true vault. Nevertheless, theycreated impressive structures through extensiveearth moving and bold architectural sculptureeither integral with the stone or as added stuccoornamentation.The so-called Governors’ Palace atUxmal, sited on a great artificial terrace, is along, horizontal building, the proportions andornamentation of which suggest the eye and hand ofa master designer. The Incas’ thriving empire wascentered high in the Andes of east-central Peru atCuzco, which flourished from about 1200 to 1533,with other cities at nearby Sacsahuaman and MachuPicchu.
Inca architecture lacks the sculpturalgenius of the Maya, but the masonry craftsmanshipis unexcelled; enormous pieces of stone weretransported over mountain terrain and fittedtogether with precision, in what is calledcyclopean masonry. See Pre.Columbian Art andArchitecture. The building systems and forms ofancient Greece and Rome are called classicalarchitecture. Greek contributions in architecture,as in so much else, defy summarization.Thearchitecture of the Roman Empire has pervadedWestern architecture for more than two millennia.The architecture that developed on mainland Greece(Helladic) and in the basin of the Aegean Sea(Minoan) belongs to the Greek cultures thatpreceded the arrival in about 1000 BC of theIonians and the Dorians.
The Minoan culture(3000-1200 BC) flourished on the island of Crete;its principal site is the multichambered Palace ofMinos at Knossos, near present-day Irklion. On thePelopnnisos near Argos are the fortress-palaces ofMycenae and Tiryns, and in Asia Minor the city ofTroy-all of them excavated by the Germanarchaeologist Heinrich Schliemann in the lastquarter of the 19th century. Mycenae and Tirynsare believed to represent the Achaean culture, thesubject of Homer’s epic Iliad and Odyssey. SeeAegean Civilization. The Greek temple emerged asthe archetypal shrine of all time.
Unlike theEgyptians, the Greeks put their walls inside toprotect the cella and their columns on theoutside, where they could articulate exteriorspace. Perhaps for the first time, the overridingconcern is for the building seen as a beautifulobject externally, while at the same timecontaining precious and sacred inner space. Greekarchitects have been praised for not crushing theviewer with overmonumentality; yet they found itappropriate to build temples on basically the sametheme ranging in size from the tiny Temple of NikeApteros (427-424 BC) of about 6 by 9 m (about 20by 30 ft) on the Athens Acropolis to the giganticTemple of Zeus (circa 500 BC) at Agrigento inSicily, which covered more than 1 hectare (morethan 2 acres). The Greeks seldom arranged theirmonuments hierarchically along an axis, preferringto site their temples to be seen from severalviewpoints in order to display the relation ofends to sides. In successive efforts during manycenturies the Greeks modified their earliermodels.
Concern for the profile of the building inspace spurred designers toward perfection in thearticulation of parts, and these parts becameintellectualized as stylobate, base, shaft,capital, architrave, frieze, cornice, andpediment, each representing metaphorically itsstructural purpose.Two orders developed more orless concurrently. The Doric order predominated onthe mainland and in the western colonies. Theacknowledged Doric masterpiece is the Parthenon(448-432 BC) crowning the Athens Acropolis (seeParthenon). The Ionic order originated in thecities on the islands and coasts of Asia Minor,which were more exposed to Asian and Egyptianinfluences; it featured capitals with spiralvolutes, a more slender shaft with quite differentfluting, and an elaborate and curvilinear base.
Most of the early examples are gone, but Ionic wasused inside the Propylaea (begun 437 BC) and inthe Erechtheum (begun 421 BC), both on the AthensAcropolis. The Corinthian order, a laterdevelopment, introduced Ionic capitals elaboratedwith acanthus leaves. It has the advantage offacing equally in four directions and is thereforemore adaptable than Ionic for corners.Cityplanning was stimulated by the need to rebuildDorian cities after the end (466 BC) of thePersian Wars and again by the challenge of newcities established (beginning 333 BC) by Alexanderthe Great. The plan of Miletus in Asia Minor is anearly example of the gridiron block, and itprovides a prototype for the disposition of thecentral public areas, with the significantmunicipal buildings related to the major civicopen spaces. A typical Greek agora included atemple, a council house (bouleuterion), a theater,and gymnasiums, as well as porticoes giving shapeto the edges of the open space. Greek domesticarchitecture transformed the Mycenaean megaron(hearthroom) into the house with rooms disposedabout a small open court, or atrium, a theme laterelaborated in Italy, Spain, and North Africa. SeeGreek Art and Architecture; House.
Romanarchitecture continued the development nowreferred to as classical, but with quite differentresults.Unlike the tenuously allied Greekcity-states, Rome became a powerful,well-organized empire that planted itsconstructions throughout the Mediterranean world,northward into Britain, and eastward into AsiaMinor. Romans built great engineering works-roads,canals, bridges, and aqueducts.
Their masonry wasmore varied; they used bricks and concrete freely,as well as stone, marble, and mosaic. Use of thearch and vault introduced curved forms; curvedwalls produced a semicircular space, or apse, forterminating an axis. Cylindrical and sphericalspaces became elements of design, well suited tothe grandiose rooms appropriate to the Romanimperial scale. Barrel or tunnel vaults areinherently limited in span, and they exert lateralthrust.Two Roman inventions of enormousimportance overcame this. First was the dome,inherently more stable than the barrel vaultbecause it is doubly curved, but also limitedbecause it thrusts outward circumferentially. Itwas possible for Hadrian to rebuild (AD 118-28)the Pantheon in Rome with a dome 43 m (142 ft)above the floor, but only by encircling it with amassive hollow ring wall 6 m (20 ft) thick thatencloses eight segments of curved units. Thus, adome provides for a one-room building but cannoteasily be combined with other domes to make alarger space.
The second important invention wasthe groin vault, formed by the intersection of twoidentical barrel vaults over a square plan. Theyintersect along ellipses that go diagonally to thecorners of the square.Because the curvature is inmore than one direction, each barrel tends toreinforce the other. The great advantage of thegroin vault is that it can be placed on four piers(built to receive 45 thrust), leaving the sides ofthe square for windows or for continuity withadjoining spaces. In the great Roman thermae(baths) and basilicas (law courts and markets),rows of square groin-vaulted bays (or units)provided vast rooms lighted by clerestory windowshigh on the long sides under the vaults. TheRomans introduced the commemorative or triumphalarch and the colosseum or stadium. They furtherdeveloped the Greek theater and the Greek house;many excellent examples of houses were unearthedin the excavations of Pompeii and Herculaneum,towns that were buried in the violent eruption ofMount Vesuvius in AD 79.
The Roman genius forgrandiose urban design is seen in the plan ofRome, where each emperor left a new forum,complete with basilica, temple, and otherfeatures.Their plans are axially organized, butwith greater complexity than heretofore seen. Themost remarkable among the great complexes isHadrian’s Villa (AD 125-32) near Tivoli, whichabounds in richly inventive plan forms. The Greekorders (Doric, Ionic, Corinthian) were widelyadopted and further elaborated. But the Romansultimately trivialized them by applying themindiscriminately, usually in the form of engagedcolumns or pilasters with accompanying cornices,to both interior and exterior walls as a form ofornamentation. They lost in the process theorders’ capacity to evoke a sense of the loadsbeing sustained in post-and-lintel construction.
See Roman Art and Architecture. Two majorarchitectural developments were initiated byhistoric religious events.The first occurred in312, when the Roman emperor Constantine the Greatconferred recognition on Christianity, which ledto the development of Christian architecture. Thesecond, the promulgation of Islam in about 610 bythe Prophet Muhammad, spawned Islamicarchitecture. Constantine the Great’s removal in330 of the imperial capital to Byzantium, whichbecame Constantinople (modern Istanbul), separatedthe Christian church into East and West and set inmotion two divergent architecturaldevelopments-Early Christian and Byzantine-eachtaking as its point of departure a different Romanprototype.
The term Early Christian is given tothe basilican architecture of the church prior tothe reintroduction of vaulting about the year1000. The surviving churches in Rome that mostclearly evoke the Early Christian character areSan Clemente (with its 4th-century choirfurnishings), Sant’ Agnese Fuori le Mura (rebuilt630 and later), and Santa Sabina (422-32). WhileByzantine architecture developed on the conceptcalled the central church, assembled around acentral dome like the Pantheon, the Western orRoman church-more concerned with congregationalparticipation in the Mass-preferred the Romanbasilica.Early models resembled large barns, withstone walls and timber roofs. The central part(nave) of this rectangular structure was supportedon columns opening toward single or doubleflanking aisles of lower height. The difference inroof height permitted high windows, calledclerestory windows, in the nave walls; at the endof the nave, opposite the entrance, was placed thealtar, backed by a large apse (also borrowed fromRome), in which the officiating clergy wereseated. The Eastern emperor Justinian I was incontrol of Ravenna during his reign (527-65). Someof the constructions there can be consideredByzantine, as they featured mosaic muralcompositions in Byzantine style.
Two of Ravenna’sgreat churches, however-Sant’ Apollinare Nuovo(circa 520) and Sant’ Apollinare in Classe (circa530-49)-are basilican in plan.See Early ChristianArt and Architecture. Byzantine architecture hasits early prototypes in San Vitale (526-47) inRavenna and in Saint Sergius and Saint Bacchus(527) in Constantinople, both domed churches on anoctagonal plan with surrounding aisles. But it wasJustinian’s great church at Constantinople, HagiaSophia, or the Church of the Holy Wisdom (532-37),that demonstrated how to place a vast dome over asquare plan. The solution was to place the dome onpendentives, or spherical triangles, that make acircle out of the square by rounding its corners.
The pendentive can be understood by visualizingits geometry. A square drawn on the ground has twocircles, one circumscribed around it, the otherinscribed within it. A he ….