Acropolis
The citadel of a Greek city, built at its highest point and containing the chief temples and public buildings, as at Athens.
Agora
The open space in a Greek or Roman town used as a market-place or general meeting-place, usually surrounded by porticos as in a FORUM.
Intercolumniation
The distance between the centres of the bases of adjacent columns measured in multiples of the column diameters. Vitruvius established five main ratios, 1 1/2D Pynostyle, 2D Systyle, 2 1/2D Eustyle, 3D Diastyle, 4D Araeostyle.
Entasis
The very slight convex curve use on Greek and later columns to correct the optical illusion of concavity which would result if the sides were straight. Also used on spires and other structures for the same reason.
Cella
The main body of a classical temple (containing the cult image), as distinct from the portico, etc.
Talud
the incline plane in Pre-Columbian pyramid construction.
Tablero
The vertical, often ornamented plane in Pre-Columbian pyramid construction. (Example: temple platforms at Teotihuacan)
Voussoir
A brick or wedge-shaped stone forming one of the units of an arch.
Keystone
The central wedge-shaped stone at the crown of an arch or a rib vault, put in last, sometimes carved.
Pozzolana
natural cement. The Romans made this cement with ash that was blown out of the volcano Vesuvius. it is waterproof and hardens even when it is wet.
Portico
A roofed space, open or partly enclosed, forming the entrance and centrepiece of the façade of a temple, house or church, often with detached or attached columns and a PEDIMENT. It is called "prostyle" or "in antis" according to whether it projects from or recedes into a building; in the latter case the columns range with the front wall. According to the number of front columns it is called "tetrastyle" (4), "hexastyle" (6), "octastyle" (8), "decastyle" (10), or "dodecastyle" (12). If there are only two columns between pilasters or antae it is called "distyle in antis."
Oculus
A circular opening in a wall or at the apex of a dome, e.g. Pantheon, Rome.
Coffering
Decoration of a ceiling, a vault, or an arch SOFFIT, consisting of sunken square or polygonal ornamental panels. See also CAISSON; LACUNAR.
Atrium
In Etruscan and Roman architecture, an inner court open to the sky and surrounded by small rooms covered with tiled roofs sloping inwards to a rectangular opening, e.g. House of the Silver Wedding, Pompeii.
Tablinum
In Ancient Roman architecture, a room with one side open to the ATRIUM or central courtyard.
Triclinium
The dining-room in an Ancient Roman house.
Impluvium
The basin or water cistern, usually rectangular, in the centre of an ATRIUM of a Roman house to receive the rain-water from the surrounding roofs. The term is also used, loosely, for the uncovered space in the atrium as well as the water cistern.
Forum
In Roman architecture, a central open space usually surrounded by public buildings and colonnades: it corresponds to the Greek AGORA.
Colonnade
A row of columns carrying an entablature or arches.
Basilica
An Ancient Roman colonnaded hall for public use (e.g. the basilicas of Trajan and Augustus, Rome; the basilica of Constantine, Trier, Germany, survives almost intact), later adopted as a building type for EARLY CHRISTIAN churches. The term indicated function and not form, but Ancient Roman basilicas were often oblong buildings with aisles and galleries and with an apse opposite the entrance which might be through one of the longer or shorter sides. It was from public buildings of this type that Early Christian churches evolved (not from pagan religious architecture) and by the C4 they had acquired their essential characteristics: oblong plan; longitudinal axis; a timber roof, either open or concealed by a flat ceiling; a termination, either rectangular or in the form of an apse; and usually a nave with two or more aisles, the former higher and wider than the latter, lit by clerestory windows and with or without a gallery.
Nave
The main central body of a longitudinally planned building such as a Roman BASILICA or Christian church. In the latter it forms the western limb, i.e. the part west of the CROSSING; more usually the middle vessel of the western limb, flanked by AISLES.
Gable
The triangular upper portion of a wall at the end of a pitched roof corresponding to a pediment in classical architecture. It can be used non-functionally, e.g. on the portal of a Gothic cathedral. It normally has straight sides, but there are variants. A crow-stepped or corbie-stepped gable has stepped sides. A Dutch gable (characteristic of c. 1630-50) has curved sides crowned by a pediment. A hipped gable has the upper-most part sloped back. A shaped gable (characteristic of c. 1600-1650) has multi-curved sides.
Caldarium
The hot-room in a Roman bath, see THERMAE.
Tepidarium
Warm room, indirectly heated and with a tepid pool.
Frigidarium
The cool room in an Ancient Roman bath, see THERMAE; the largest and most richly decorated, with the swimming-pool and gymnasium.
Castrum
(Latin). Roman military camp, built on a common rectangular layout throughout the Empire. A castrum was surrounded by a rampart and a wall with towers, and crossed by two main streets, the cardo and decumanus, running between four gates - the porta praetoria, porta dextra, porta sinistra and porta decumana. The headquarters (praetorium) lay at their intersection, and the barracks, armoury and other essential military buildings in the four quarters made by the streets. Camps were strategically placed along the limes to secure the border.
Cardo
The principal north-south street in an Ancient Roman town or military camp, see CASTRUM.
Decumanus
An east-west-oriented road in a Roman city.
Amphitheater
An elliptical or circular space surrounded by rising tiers of seats, as used by the Romans for gladiatorial contests, the Colosseum, Rome, of AD 70-80 being the most famous. The earliest known all-masonry amphitheatre is that at Pompeii of c. 80 BC. Examples survive all over the Ancient Roman world, from Germany (Trier, c. AD 100) and France (Arles and Nimes, late C1) to North Africa (El Djem, early C3). In landscape architecture an amphitheatre is an area of similar form but with turfed terraces instead of seats.
Triumphal arch
A free-standing monumental gateway of a type which originated in Rome in the C2 BC in richly decorated temporary structures erected by Roman magistrates for such festive occasions as the triumphs decreed to victorious generals. From the late C1 BC similar structures were erected in stone, and often richly decorated with sculpture, as city gates or as entrances to fora but also frequently as urban decorations with no more than a commemorative purpose: Augustus, mostly in Italy and Gaul.
Apse
Ancient Roman in origin (found in both religious and secular contexts), an apse is a semicircular or polygonal extension to, or termination of, a larger rectangular space. Often opposite an entrance, it usually has a rounded vault. In Ancient Roman BASILICAS the praetor's it was the place of the clergy and bishop and was frequently elevated, with a passage under the seating (e.g. Hagia Irene, Constantinople). In the C9 a bay was inserted between the apse and transept, reducing the former to an adjunct of the chancel. Aisles might also terminate in apses, as would have a counter-apse. With the C12 broken-ended chevets became commoner, and ultimately the Gothic urge towards spatial amalgamation abolished the distinction between chancel and apse in favour of a deep polygonal or square-ended choir.
Narthex
In a Byzantine church, the transverse vestibule either preceding nave and aisles as an inner narthex (esonarthex) or preceding the facade as an outer narthex (exonarthex). An esonarthex is separated from the nave and aisles by columns, rails or a wall. An exonarthex may also serve as the terminating transverse portico of a colonnaded ATRIUM or quadriporticus.
Transept
The transverse arms of a cross-shaped church, usually between NAVE and CHANCEL, but also occasionally at the west end of the nave as well, and also doubled, with the eastern arms farther east than the junction of nave and chancel. The latter form is usual in English Gothic cathedrals. In Islamic architecture a heightened area in the prayer hall of a MOSQUE, between the central entrance and the MIHRAB, with an axis at right angles to the much longer QIBLA wall.
Crossing
The space at the intersection of the nave, chancel and transepts of a church; often surmounted by a crossing tower or dome.
Spolia
Materials removed from buildings of an earlier period than that in which they are incorporated, e.g. reliefs on the Arch Constantine, Rome; Roman columns in the Great Mosque, Cordoba.
Mausoleum
A conspicuous freestanding tomb intended as an enduring monument to the person or persons buried inside, as distinct from a CENOTAPH an a TUMULUS. The term derives from the mid-C4 BC tomb of Mausolus at Halicarnassus, some 40 m. (130 ft) high with an Ionic colonnade crowned with a stepped pyramid on a podium with much sculpture, the remains of which are in the British Museum, London. In Italy the Roman emperors preserved the Etruscan tradition of tomb chamber covered by tumuli, the mound being given massive architectural form and faced with marble, e.g. that of Augustus, begun 28 BC, of which only parts survive, and that of Hadrian, begun c. AD 125-30, now incorporated in Castel S. Angelo, both in Rome. From the C4 mausolea were built for Christians, e.g. that of Theodoric, Ravenna, c. AD 526. Classical style mausolea were revived by Protestants in C18 England, sometimes set in LANDSCAPE GARDENS, e.g. by HAWKSMOOR at Castle Howard, Yorkshire (1736), though more often in churchyards and CEMETERIES.
Pendentive
A concave SPANDREL leading from the angle of two walls to the base of a circular DOME. It is one of the means by which a circular dome is supported over a square or polygonal compartment (see also SQUINCH), and is used in Byzantine (Hagia Sophia, Istanbul) and occasionally Romanesque architecture (Perigueux), and often in Renaissance, Baroque, and later architecture.