The Classical World

For most of the last five centuries “classical architecture” has meant the architecture of Greece and Rome and of everything built in imitation of it. Part II of this book deals with the grammar at its heart, the orders of columns. This chapter steps back to look at the two civilisations that invented that grammar and at what they built with it: the temples, theatres, stoas and houses of the Greeks, and the concrete halls, domes, aqueducts, arches and cities of the Romans.

The two traditions are usually paired, but they were different in spirit. Greek architecture was an architecture of the perfected object: the temple standing free in its sanctuary, carved and adjusted until it seemed alive. Roman architecture was an architecture of space and system: interiors shaped in concrete, buildings of every type laid out on axes, a technology exported to a whole empire. Rome absorbed Greece, and the Renaissance received them together, but it is worth seeing them one at a time.

The Greek temple and its refinements

The Greek temple was a house for the image of a god, not a place of congregational worship: sacrifices took place at an altar in the open air in front of it. Its form, fixed in the seventh and sixth centuries BC, is described in the chapter on the temple: a walled cella on a stepped platform, surrounded by a colonnade and covered by a low-pitched timber roof ending in pediments. What concerns us here is the way the Greeks refined that simple type, above all at the Parthenon in Athens (447–432 BC).

In the 1840s the English architect Francis Penrose surveyed the Parthenon with instruments of great precision and confirmed what earlier visitors had suspected: the building contains almost no straight lines. The platform rises in a gentle curve toward the middle of each side, by about 11 cm along the 69.5 m flanks. The entablature repeats the curve. The columns lean slightly inward, the corner columns diagonally; the corner columns are thicker than the rest and set closer to their neighbours; every shaft swells in a barely perceptible curve. Vitruvius, writing four centuries later, prescribes several of these adjustments as corrections for illusions of the eye.

Whether the refinements were meant to correct illusions (a flat platform does look as if it sags, a column seen against the sky does look thinner) or to give the building an elastic, living quality, they show a culture that treated architecture as sculpture on a colossal scale. Each column drum and each block of the platform had to be cut to its own slightly different shape; the precision required was extraordinary. The Parthenon’s proportions show the same care: the ratio 4 : 9 recurs between the diameter of a column and the spacing of the columns, the width and length of the platform, and the height of the order and the width of the front.

℟The Parthenon’s ratio of 4 : 9

Let one simple ratio govern the whole: at the Parthenon the lower diameter is to the axial spacing, the width of the stylobate to its length, and the height of the order to the width of the front, all very nearly as 4 is to 9.

D : axial spacing ≈ 1.905 : 4.296 ≈ 4 : 9; stylobate 30.88 : 69.50 ≈ 4 : 9

The problem of the corner

The Doric frieze made the Greek architects’ perfectionism into a puzzle. Its rules are strict: a triglyph over the centre of every column and every intercolumniation, square metopes between them, and, at the corners, two triglyphs meeting edge to edge. The third rule is incompatible with the other two, because the corner of the frieze lies outside the axis of the corner column by half the depth of the architrave. Something has to give.

The Greeks of the Classical period chose to keep the corner triglyph and the square metopes and to move the corner column inward, narrowing the last intercolumniation; builders in Sicily sometimes spread the adjustment over the last two bays. Vitruvius reports that some Hellenistic architects gave up the Doric order altogether because of the difficulty, and recommends instead a half-metope at the corner, which kept the columns evenly spaced. That became the Roman and Renaissance practice. Two civilisations looked at the same problem and preferred to break different rules.

Stone without mortar

Greek builders worked almost entirely in cut stone laid dry. Walls were of coursed ashlar, whether isodomic, with equal courses, or pseudisodomic, with courses of different heights; blocks were joined with iron clamps and dowels set in lead, and their contact faces dressed by anathyrosis to joints so fine they can scarcely be seen. Column shafts were built of drums, centred on wooden plugs, and fluted only after the column was erected. The roofs, though, were of timber, and the span of a Greek building was limited by the length of its beams. Greek architecture never developed the vault on a monumental scale; its interiors are modest, and its grandeur is external.

The theatre and the city

Beyond the sanctuary, the Greeks created the settings of civic life. The agora, the open square of the city, was framed by long colonnaded halls, the stoas; there were council houses, gymnasia and stadiums. The theatre began as a circle of beaten earth where the chorus danced, with spectators on the slope of a hill; by the fourth century BC it had become a semicircle of stone seats, the cavea, wrapped round a circular orchestra, with a stage building behind. The theatre at Epidauros, of the late fourth century, seats some 14,000 people, and a word spoken in the orchestra is audible in the top row.

Vitruvius gives the geometry of both the Greek and the Roman theatre. In the Greek plan three squares are inscribed in the orchestra circle; the side of one fixes the front of the high, narrow stage, and the scene building stands on a tangent behind. The Roman plan uses four equilateral triangles, which bring the stage forward into the circle and leave only a half-orchestra, filled with the seats of senators.

The Greeks also planned new cities on grids of streets at right angles, a practice associated with Hippodamos of Miletos in the fifth century BC and spread by the colonies and by the Hellenistic kings. Hellenistic architecture (Pergamon, Priene, Didyma) grew grander and more theatrical, with terraces, long axial approaches and buildings conceived as parts of a composed scene. It was this Hellenistic architecture that Rome encountered as it expanded eastward in the second century BC.

Rome: concrete and space

Rome’s early temples followed Etruscan practice: a high podium, a deep porch of widely spaced columns, a single stair at the front. From the Greeks it took the orders, the theatre and the colonnade. What it added was a new material. Roman concrete (rubble laid in a lime mortar made with the volcanic ash called pozzolana) could be built into walls, vaults and domes of any shape and almost any size, and it did not need skilled stonecutters, only organised labour. Facings of stone and brick served as permanent formwork and were usually hidden under stucco or marble.

With concrete the Romans could shape interiors: barrel vaults, groin vaults, domes, apses, curving walls. The great bath buildings (thermae) of the empire strung vaulted halls of different shapes and temperatures along symmetrical axes; the Basilica of Maxentius (AD 308–312) spanned its nave with three colossal groin vaults on piers. The summit of the method is the Pantheon, whose rotunda would contain a sphere 43.3 m across; it is treated in detail in the chapter on domes.

℟A sphere within a cylinder

Make the height of the rotunda to the top of its dome equal to its diameter, so that the interior would exactly contain a sphere resting on the floor: the drum rises to the centre of the sphere and the dome is its upper half.

Pantheon: Ø = height = 43.3 m (150 Roman feet); drum = ½ Ø

The orders did not disappear; they changed their role. On the Theatre of Marcellus and the Colosseum, engaged columns and continuous entablatures frame each arch of the arcades, one order above another (see The arch framed by an order and Stronger below, lighter above). The column no longer carries the building; it measures and articulates it. The triumphal arch, a wall pierced by one or three arches, framed by columns on pedestals and crowned by an attic for the inscription, is the purest expression of this Roman synthesis of Greek order and Roman arch.

℟The triumphal arch

Pierce a massive rectangular pier with one arch, or with a tall central arch between two lower ones; frame the openings with columns on pedestals carrying an entablature, and crown the whole with a high attic for the dedicatory inscription.

Arch of Titus: 13.5 × 15.4 m, one opening 5.4 × 8.3 m; Arch of Constantine: 25.9 × 21 m, openings 6.5 × 11.5 m and 3.4 × 7.4 m

Water and roads

Roman engineering served whole cities. Aqueducts brought water from springs tens of kilometres away, running by gravity alone in covered channels at very slight gradients, through tunnels under hills and across valleys on bridges of arches. The water ran to distribution tanks and then to public fountains, baths and private houses. The Pont du Gard, which carried the aqueduct of Nîmes over the river Gardon around the middle of the first century AD, stacks three tiers of arches to a height of nearly 49 m; the aqueduct as a whole falls only about 12.6 m over some 50 km.

The house

Most Romans lived in insulae, apartment blocks of several storeys over street-level shops; the wealthy lived in the domus, a house turned inward to its own courts. Vitruvius describes its sequence: a narrow entrance passage, the fauces; the atrium, a hall whose roof sloped inward to an opening, the compluvium, above a basin, the impluvium; the tablinum opposite the entrance; and beyond it the peristyle garden surrounded by colonnades, with dining rooms and summer rooms around. Each room is proportioned from the atrium, and the atrium from one of three ratios.

The houses excavated at Pompeii and Herculaneum, buried by Vesuvius in AD 79, show that Vitruvius’s scheme was an ideal rather than a rule strictly followed; but the axial sequence of fauces, atrium, tablinum and peristyle, and the idea of a house built around light-filled courts, are everywhere.

Vitruvius and the survival of the classical

The only architectural treatise to survive from antiquity is the Ten Books of Vitruvius, written in the early years of Augustus. It is the voice behind most of the rules in this chapter: the curvature of the stylobate and the thickening of corner columns, the Doric corner, the plans of theatres and houses, the walls of opus incertum and reticulatum, the gradients of aqueducts. Vitruvius was a practising engineer rather than a great architect, and his book is uneven, but it gave later ages something no other ancient art had: a written theory.

The buildings themselves did the rest. Ruined, stripped of their marble and reused as churches, fortresses and quarries, they remained visible across Europe and the Mediterranean. The Early Christian basilica grew from the Roman hall; the Byzantine dome from the Roman vault. From the fifteenth century architects measured the ruins with new eyes, and the Renaissance, the Baroque and the Neoclassical are successive attempts to recover what they found. The rediscovery of the Greek buildings themselves, from the mid-eighteenth century, produced the Greek Revival and eventually Penrose’s survey, the moment when the rules of the Parthenon were read not from a book but from the stones.