Trajan and Hadrian Part 2 | Roman Architecture | Second edition
ground floor open onto the street, and behind them further shops open into a curved corridor which ran around the upper half-domed hall on the NW side of the large hemicycle. On the level below them are further shops which are lit by light-wells over the extrados of the halfdome, a system analogous to the octagonal room of Nero’s Domus Aurea. As the half-domed room itself was surrounded on all sides by buildings it can have been lit only by the oculus.
The shops on the east side of Via Biberatica were three storeys high, the upper two belonging to a market hall, accessible by a staircase off Via Biberatica (Figure 8.6). On the lower floor of the hall two rows of six barrel-vaulted shops faced each other across a central concourse, an arrangement reminiscent of modern shopping arcades. Above these were two further rows of six shops, once again barrel-vaulted, but shallower because of the space taken up by the access corridor. The roofing of the central space, by means of six cross-vaults, is particularly interesting, because the cross-vaults were not contiguous with the barrel-vaults of the six rooms each side of the upper part of the hall. Instead, a space was left between them to light the access corridors and shops of the upper storey, as well as providing extra lighting to the lower floor of the hall. To stabilise the cross-vaults two rows of seven flying buttresses ran between the springings of the cross-vaults and the barrel-vaults of the shops. This is another example of lighting achieved by light-wells over or near the extrados of a vault.
As Rome became an increasingly important administrative hub of the Empire, so the functions of the city centre multiplied. The new Imperial fora usurped land which had hitherto been used for trade and commerce. The Temple of Peace, for example, was built on the site of the old macellum of 179 bc once its marketing activities had been transferred away from
Figure 8.6 Rome, Markets of Trajan, market hall: axonometric view. In the foreground is the street which later became the Via Biberatica.
the civic centre. The creation of Trajan’s Markets was a further step in removing from the old Forum and its surrounding area traditional commercial and business activities which were now inappropriate to its new dignity as the civic focus of the Roman Empire. It has been calculated that the complex gave Rome some 150 new shops and offices in an environment noticeably similar to modern planned shopping centres.
In conjunction with his forum Trajan began renovating the Forum Julium and reconstructed the Temple of Venus Genetrix, which was inaugurated in ad 113 (Figures 3.2 and 3.3). The barrel-vaults of some rooms on the SW side of the Forum were demolished and new barrel-vaults built to support a semicircular latrine above them. The basilica Argentaria (of the bankers), which was built to the NW of the latrine at Forum level was divided into three naves by brick piers. It followed the line of the SW portico of the Forum Julium and new shops were added above it. Architecturally it provided a link between the Forum Julium and the SW hemicycle of the Forum of Trajan.
Trajan showed his concern for the economy of Rome and Italy in several other respects. His harbour works at Ostia (Figure 6.16) and the new markets in Rome reflected the need to protect Rome’s grain supply and the distribution of the ever-increasing flood of goods and services. Trajan therefore involved himself in improving communications throughout Italy. Milestones record repairs to the Via Sublacensis (ad 103–105), Latina (ad 105), Aemilia (ad 100), Puteolana (ad 109), and Salaria (ad 110). Improvements were also made to the Via Clodia and the Via Cassia, and he continued the repairs to the Via Appia which Nerva had begun. A new roadbed was built where the road crossed the Pontine marshes. In ad 112 he created a new coastal route for it at Terracina, by cutting away Pisco Montano to a depth of 120 Roman feet (36 metres), as an inscription records. In ad 109 he began a new road, called the Via Traiana (begun ad 109) from Beneventum (Benevento) to Brundisium (Brindisi), the port for ships bound for the eastern Mediterranean. It offered an alternative route to the old Via Appia, saving a good day’s journey (Strabo 6.3.7). To mark the beginning of the new road a triumphal arch was erected at Benevento (ad 117), strikingly similar in design and scale to the earlier Arch of Titus in Rome, so similar in fact that some have thought the latter Trajanic (Figure 8.7). The Arch of Trajan at Ancona was of similar type but with somewhat taller proportions. The Benevento arch is better preserved than the Arch of Titus because all its sculptural panels survive. Those facing the city referred to Trajan’s work in Italy, while those facing the countryside praised his good works in the provinces. The terminus of the Via Traiana, an eminence overlooking the harbour, was marked by two tall columns of white marble, one of which survives intact. Its capital is elaborately carved with the heads of Jupiter, Mars, Neptune and Minerva on its four sides. Seen from the road the two columns framed the harbour mouth through which ships sailed for Greece and beyond, carrying travellers on the next leg of their journey.
Trajan had increased the empire to its greatest geographical extent. Hadrian (ad 117– 138) was aware that the huge inland empire he had inherited would not only cause security problems, but change the whole nature of the Roman empire from a coastal entity to a continental one. His ideal was a secure, self-sufficient empire where peace, prosperity and security reigned. Therefore soon after his succession he relinquished some of Trajan’s eastern conquests and was with difficulty persuaded to retain Dacia, where romanisation was already well under way. Hadrian’s reign was peaceful, except for the continued revolt in ad 115–117 of the Jews of the diaspora (Cyrenaica, Egypt, Mesopotamia and Cyprus), which was repressed with great loss of life. Another uprising, called the Bar Kokhba revolt (ad 132–136) was also crushed. Hadrian attempted to completely destroy Judaism, banning the Torah, replacing Judaea with Syria Palaestina and re-founding Jerusalem as Aelia Capitolina.
Figure 8.7 Beneventum (Benevento), Arch of Trajan, ad 117, side facing the city.
Hadrian made no concealment of his admiration for the Greeks, whom he favoured more than the Romans. Encouraged by his Greek advisor, Polemo of Laodicea, he aped Greek fashions and was the first in a long line of Roman emperors to wear a beard. Countless statues of the Bithynian boy, Antinous, who was constantly in Hadrian’s company, flooded the empire, and when he died prematurely in ad 130 Hadrian had him deified. Although he endowed the capital with new buildings he showed just as great an interest in the provinces. He spent almost half his reign travelling throughout the empire, a fact which caused resentment in Rome. From ad 121–125 and again from ad 128–133 he was out of Rome visiting Gaul, Germany, Raetia, Noricum, Britain, Spain and Morocco. In the east he visited Greece, Asia Minor, Syria and Egypt. In ad 134–135 he spent time in Palestine. All over the empire his presence is attested by bridges, roads, baths and other public monuments; whole cities were rebuilt and new ones founded. Rome, which had for so long imported works of art, craftsmen and wealth from the provinces, began to export its own art and as a result provincial cities grew in wealth, splendour and power.
The Pantheon (Figure 8.8), one of the great masterpieces of Roman architecture, is exceptionally well-preserved, enabling us to experience its effects at first hand. The building has survived in such excellent condition because in ad 609 the Byzantine emperor, Phocas, gave the building to Pope Boniface IV, who converted it into the church of St. Maria ad Martyres. That is not to say that the building has not been much damaged over the ages. The mutilation began in ad 663 when the Byzantine emperor Constans II removed the bronze tiles of the dome and sent them to Constantinople. The pediment nowadays lacks any form of decoration, although a study of the fixing holes has revealed that the fastigium (pedimental) sculpture
Figure 8.8 Rome, Pantheon, the porch, ad 118–125.
was an imperial eagle with outspread wings within a ribboned wreath. Even the bronze letters of the inscription on the façade are late 19th century replacements of the original gilt bronze letters, which had long since been removed. In 1626 the Barberini Pope, Urban VIII (1623–1644), replaced the three left-hand (east) grey granite columns of the porch, which had been damaged in the Middle Ages, with shafts of pink Aswan granite removed from other ancient buildings. At the same time, he removed the bronze girders of the portico which weighed 200 tonnes and melted them down to make cannon for Castel S. Angelo. The facing of white stucco on the exterior of the rotunda has also disappeared. Even the bronze doors, although ancient, are far too small and are therefore not the originals
The Pantheon was erected early in Hadrian’s reign, as is shown by brickstamps which fix its date to between ad 118–125. Agrippa built the first Pantheon in 27 bc, but it was a victim of the fire of ad 80 and was rebuilt by Domitian. This building in turn was struck by lightning and burned at the time of Trajan (Orosius, 7.12.5). However, the inscription over the portico commemorates the original builder, Agrippa, in accordance with Hadrian’s policy of not putting his name on any monument except the temple of his adoptive father, Trajan (SHA, Hadrian 19.9). There was a long narrow forecourt in front of Hadrian’s building, lower than the present piazza. A broad flight of four yellow Numidian marble steps, 1.32 metres high, now buried, led up to the pronaos (porch), which measured 34.20 × 15.632 metres. It is likely that Hadrian built the traditional columnar porch in order to preserve visual continuity between the new building and the old, while at the same time concealing the enormous domed interior until the last moment. The porch is octastyle, with four rows of two granite columns behind creating three aisles (Figures 8.8 and 8.9). The central aisle led to the main door and the side aisles each terminated in an apse in which stood statues of Augustus and Agrippa. Even today one is amazed at entering a vast domed room when the porch had led one to expect a traditional cella.
Figure 8.9 Rome, Pantheon, ad 118–128: plan and section, showing filling materials.
An oddity of the intermediate block behind the porch is the second, higher pediment behind the main one (Figure 8.8). As the second pediment is exactly 10 Roman feet above the main pediment and the columns of the porch are 50 Roman feet (14.8 metres) high, it has been argued that the porch was originally designed for 60-foot (17.76 metres) columns which would have produced a more harmonious result (Figure 8.10).12 Perhaps columns of this height were not available at the time or perhaps available supplies had been used by Hadrian for the Temple of Trajan as an act of piety. Therefore the present 50-foot columns were used instead, a plausible suggestion as the grey granite columns came from the quarry of Mons Claudianus, which was difficult of access and deep in the eastern desert of Egypt. It is about as far from Rome as it was possible to go in the Roman Empire.
The proportions of the interior were based upon simple, solid geometry. The internal diameter and height of the rotunda are the same, c. 44.40 metres (150 Roman feet), and the dome springs 75 Roman feet above the pavement, which means that a sphere of the same diameter as the rotunda would exactly fit inside the building. The walls of the drum were founded upon a great ring of concrete, 7.30 metres wide and 4.5 metres deep. The drum has three external cornices which divide it into three horizontal zones (levels 1, 2 and 3). Internally the drum has only two cornices, the lower above the columns and pilasters of the exedras, and the upper above the window zone at the point where the dome springs. Externally the dome appears to spring from the top of level 3 (Figure 8.9), giving it a somewhat squat appearance when seen from a distance.
The drum, of brick-faced concrete, has walls over 6 metres thick, but the envelope of the dome diminishes to 1.54 metres at the top (Figure 8.9). The caementa (filling stones) were
Figure 8.10 Rome, Pantheon, porch as planned: diagram. (After M. Wilson Jones, Principles of Roman Architecture. [New Haven, CT: Yale University Press, 2000], figure 10.12.)
graded so that travertine was used in the foundations, tufa and travertine in the lower part of the drum, tufa and brick higher up, brick at the base of the dome, tufa and brick higher up, and pumice and volcanic scoria in the highest part of the dome. According to Robert Mark, ‘the light aggregates used in the dome were more effective in reducing stress than the coffering whose effect was negligible’.13 The dome has five rows of 28 stepped coffers, which, according to Renaissance drawings, were decorated with relief stucco mouldings and bronze rosettes, probably gilded (Figure 8.11). The dome has no crown, but terminates in a circular opening (oculus) 8.9 metres (30 Roman feet) across. The oculus is extremely efficient in lighting the room even though it represents less than 4% of the floor area, but it also admits rain which is why the floor is slightly crowned (it is 0.30 metre higher in the middle than at the edges). The floor was paved in 10 foot square panels divided by 3-foot-wide strips of pavonazzetto. The panels were filled alternately with seven-foot squares of pavonazzetto bordered with porphyry, and red porphyry or grey granite roundels bordered with giallo antico. There is no evidence of any ribbing in the dome, which means that it would have had to be supported on a full timber scaffolding until the whole structure had set. The amount of timber needed for this operation goes a long way to explaining why the Romans later began to adopt tile-clad vaults and ribbing.
The interior skilfully conceals the elaborate system of support and consolidation, which is better seen on the outside of the building. Looking at level 2, what seem to be arches are in fact the ends of vaults built of radially laid bipedales to control the loads imposed by the dome above (Figure 8.12). They extend the whole way through the drum of the building and correspond to the eight interior exedras. It will be observed that a second set of arches span
Figure 8.11 Rome, Pantheon, the dome from below.
Figure 8.12 Rome, Pantheon: cutaway drawing to show the structure of the drum. (After W. L. MacDonald, The Architecture of the Roman Empire 1, plate 106.)
MacDonald, The Architecture of the Roman Empire 1, plate 106.)
the space between the eight radial vaults. These are arches, not vaults, and there is a second set of them on the inner side of the drum, which form the heads of the ‘windows’ in the upper part of the interior wall. There is another set of eight vaults in level 3, which internally correspond to the lowest two rows of coffers of the dome. Within the piers between the interior exedras, behind the aedicules, are eight semicircular rooms covered with half-domes, facing outwards and repeated on all three levels (Figure 8.9). The object of all these cavities was doubtless to help the concrete dry out evenly and to distribute settlement cracks.
In plan the interior consists of 16 segments, one formed by the entrance doorway and another by the big, round-headed apse opposite (Figure 8.9). Two curved exedras face each other across the building, and between are four square ones. In each of these six exedras is a pair of giallo antico Corinthian columns framed by pilasters. The other eight segments are the aedicules capped with triangular and segmental pediments. The columns in the exedras carry a horizontal entablature which runs around the whole interior, breaking off only at the doorway and the apse opposite, both of which carry arches which break into the window zone above. The upper part of the wall is punctuated by 14 blind windows, eight of which are structurally the product of the segmental arches spanning the space between the eight vaults. Originally the windows stood on a high socle of Phrygian purple with four slender Corinthian pilasters of red porphyry between. These were removed in 1747 and replaced by the present pedimented windows alternating with plain panels of marble. A portion of the original decoration, known from prints, has been reconstructed to the right of the apse.
There has been considerable speculation, especially recently, as to what the building was for. It was Dio Cassius (53.27.2) who first speculated that the name, Pantheon (all the gods), comes from the many statues of divinities placed around the building or the fact that the dome resembles the heavens. Many scholars have promoted a cosmic explanation of the building; others find the solution in mathematics, regarding the spatial relationship between drum and cupola as Archimedean. Furthermore, the number of coffers in the dome is 28 × 5 and since 28 is a perfect number, because it is the sum of its divisors, the dome can be regarded as having attained neo-Pythagorean perfection. Whatever explanation is given it is clear that the Hadrianic Pantheon was not a temple dedicated to a deity. Ancient authors never refer to the Hadrianic Pantheon as a temple and even the inscription does not mention any deity. Dio Cassius (69.7.1) speaks of Hadrian holding audiences there and no doubt the emperor liked to appear there surrounded by statues of the gods. The Pantheon has more in common with the halls of secular structures than to sacred ones, and it is perhaps best to regard the Pantheon as an imperial hall. From Choisy onwards there has been much discussion as to whether Apollodorus of Damascus was the architect of the Pantheon. Some now believe that the Pantheon was begun by Trajan and finished early in Hadrian’s reign. That is to say, before Hadrian’s break with Apollodorus, after which a new architectural style appeared in Rome, akin to that of Asia Minor. Furthermore, the Pantheon uses the kind of neo-Augustan ornament found in the Forum of Trajan which was favoured by Apollodorus.
In the 17th century Pope Urban VIII regarded the Pantheon as the most celebrated edifice in the whole world. Certainly the Pantheon has been one of the most influential ancient buildings throughout the ages. A similar but smaller version was built at Ostia, the Round Temple near the forum (ad 230–240). Two early fourth century ad buildings, the ‘Tor degli Schiavi’ on Via Praenestina and the Tomb of Romulus on the Via Appia Antica, have respectively a tetrastyle and a hexastyle porch attached to a domed rotunda. Both have the neat unity between rotunda and porch, which may have been intended in the Pantheon. The Pantheon has inspired architects such as Palladio in the 16th century (the Villa Rotunda at Vicenza and the Maser chapel), Bernini in the 17th century (St. Maria dell’Assunzione at Ariccia), Lord Burlington in the 18th century (Chiswick House) and Thomas Jefferson in the 19th century (Monticello, and the Library at the University of Virginia). James Wyatt built a Pantheon in London (1770) and Canova a Tempio at Possagno (1819 onwards), while the church of St. Mary at Mosta in Malta (1833–1860) has what is still the largest masonry dome in the world. Hadrian’s most extravagant and expensive project was the villa he built near Tivoli. This vast complex stretched for a kilometre on an elevated plateau to the SW of the town (Figure 8.13). Although the villa is comparatively low-lying it still commands a view to Rome, so that the dome of St. Peter’s is just visible on the horizon. Hadrian began work on the project early in his reign, about ad 118, starting from a moderate-sized Republican villa which may have been owned by the Empress, Sabina. As the plan expanded he began to incorporate into it buildings which echoed those of Greece and the east (SHA, Hadrian 26.5) so that, walking in the Stoa Poikile of the Athenian Agora, along the Canopus canal lined with copies of the Caryatids of the Erechtheum, or through the Vale of Tempe, he could re-live his travels.
It is not clear how much of this imperial Xanadu was planned when work began, although the site chosen suggests that the original scheme was an ambitious one. Some of the original fabric of the Republican villa was reused, the most conspicuous survivals being the nymphaeum on the NW side of the courtyard of the ‘libraries’ and the cryptoporticus which opened off the SE side. To the NE of the courtyard was a complex which has been identified as a guest wing for visitors. It consisted of a long paved corridor with five rooms opening off each side, and a large, perhaps communal, reception room at the end. Each of the ten rooms
Figure 8.13 Tibur (Tivoli), Hadrian’s Villa, ad 118–134: general plan.
had three recesses, presumably to take three couches or beds. The pavements in each case were of black and white mosaic, plain where the couches or beds would have been with a more elaborate geometric pattern in the middle. To the SE of the courtyard on a higher level was a large complex of nymphaea and courtyards, including the well-known courtyard of the Doric piers. The fluted white-marble piers, rectangular in plan, supported a barrel-vault which ran around all four sides of the open courtyard.
Starting from the original villa the architect began to build a series of loosely related complexes, each following a different alignment dictated by the terrain (Figure 8.13). The main parts of the villa to be discussed are (1) the Vestibule, (2) the ‘Poikile’, (3) the Island Villa, (4) Piazza d’Oro, (5) the Triclinium/ Hippodrome and upper rooms, (6) the Small Baths, (7) the Large Baths, (8) the Canopus/Serapeum and (9) the peripheral buildings. The Vestibule was approached from the NW by a road which led from a branch of the Via Tiburtina; another road ran parallel to it for vehicles leaving the Villa. Visitors would have alighted and climbed a broad staircase up to the vestibule which consisted of a large peristyle, square on three sides and apsidal on the fourth with a formal garden in the middle. To the west was a courtyard with a temple at the end and to the east a great hall on the same axis as the Canopus/Serapeum. Beyond that was a curved peristyle between the Large and Small Baths. On a lower level subterranean corridors led to the praefurnia (furnaces) of the Large and Small Baths and the ‘100 small rooms’ of the ‘Poikile’.
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