1. Introduction: the archaeology and topography of Rome
Jon Coulston and Hazel Dodge
Throughout her history Rome has been a centre of power, on a small scale initially, but steadily growing to form an empire which, for the first and last time, unified the Mediterranean world. In economic terms the influence of Rome eventually encompassed the whole of Eurasia and northern Africa. The city as consumer of mass imports (foods, water, luxuries, slaves, animals, building materials and people) grew physically in both extent and architectural complexity. Evolving building materials and techniques acted as a barometer of wealth and territorial power. The earliest structures, the huts on the Palatine (Figs. 1.1, 2.5), left only the negative imprint of sunken floors and post-holes, but requirement for larger sacred and public buildings led to the use of less perishable inorganic materials, terracotta and local tufa stones (Smith, Cornell in this volume). These began to seriously impact the archaeological record, and an increasing range of stones reflected spreading control of the Tevere (Tiber) valley and Latium (Gabian, Alban and Veian tufas; DeLaine in this volume). Hellenising cultural influences from southern Italy and further east placed a premium on hard, white stones for buildings with fine sculptural detail (white-plastered tufa, travertine, eventually marble). Finally, under the emperors, the stone resources of the whole Mediterranean and its hinterlands were organised for exploitation in a polychrome display, which consciously emphasised territorial power and technical achievement.1 There was inflationary competition between emperors and their predecessors in the provision of public amenities, such as baths or games, on an ever-increasing scale and level of luxury (Dodge, Coleman in this volume). Hand in hand with the need for buildings of increasing size to serve an ever-growing population was the development of concrete (opus caementicium) as a building material. This employed economic, mass-producible local resources in efficient, durable, vaulted structures (DeLaine in this volume).
Ancient Rome was certainly a huge urban development for any pre-industrial society to maintain, and modern scholars have tried every means to quantify her scale. Population has been calculated using overall area, built up and open space hectarage, funerary inscription statistics, and comparative modern population densities. Ancient figures for numbers of domestic dwellings by type (domus and insula), corn-dole recipients, and quantities of corn imports have all been pressed into service. Thus it has been postulated that up to 1,200,000 people lived in Rome at her 1st–2nd century AD height.2 However, every method of calculation and set of statistics runs into problems. The most fundamental is that the modern desire to quantify Rome’s scale uses evidence provided by an ancient society which had no real necessity for, nor ability to achieve, exactitude. Figures were quoted in the sources precisely to express magnitude, to reflect glory on the metropolis, or to laud the beneficent patron. Thus, the 4th century AD Regionary Catalogues presented statistics, which appear authoritative through their very detail (see Appendix). Nevertheless, close examination reveals them to have been unusable for any ‘official’, administrative purpose, such as feeding or policing the city, or maintaining the urban fabric. The arithmetic is sloppy, with numbers spelt out in detail not tallying with quoted totals.3 Rather, these figures reflect the scale of Rome taking on a life of its own, drawing in the wonder and awe of observers by its sheer quantity of statues, temples, basilicas, theatres, amphitheatres, circuses, streets, houses, mansions, military bases, aqueducts, baths, fountains, warehouses, bakers, cemeteries, and even public lavatories, churches, and brothels.4
When the economic tide receded from the 3rd century AD onwards, the urban fabric remained for future generations to live in, adapt, and continue to marvel at. The skeletons of massive buildings, their original functions often forgotten, remained to constantly remind of past glories and to provide a language for expressing present and future aspirations. The transformation of Rome into a christian capital during the 4th century ensured her a continuing central place in medieval and modern history, and continuing patronage by a series of rulers concerned with a world stage.5 The ‘idea’ of Rome has been employed through epigraphy, numismatics, art and architecture to strengthen and project the successive regimes of Late Roman and Byzantine emperors, popes, Holy Roman Emperors and other western monarchs, secular local governments, Italian kings, a fascist dictator, and the post-war Italian republic.6 Rome, like an animal in hibernation living on stored resources, has always fed on herself for inspiration and physical means. The millions of tons of stone imported by the ancient emperors were thereafter available for recycling into churches, palazzi and other monuments. The thousands of inscriptions and artworks were there to be collected and emulated.7
Underlying and channelling this urban development are the fundamentals of geology, geomorphology and topography that are now rather difficult to envisage in the presence of the modern city. Much work has been done on hilltop and valley geology, dominated by volcanic deposits and fluvial erosion (Fig. 1.2).8 Indeed, the action of the Tiber and its tributary streams is critical to the city’s location (Dodge in this volume). Erosion of the Esquiline plateau created a series of peninsulas and linked or isolated hills, divided by steep-sided valleys, which open out onto the flood plain. The Palatine Hill was small enough to be defended at an early date but large enough for a growing community (Smith in this volume). The Capitoline Hill was suitably small and defensible for it to subsequently become the acropolis of the expanded regal city. The Tiber Island provided the lowest fording-point above the mouth of the river and an overland line of communication between Etruria to the north-west and Latium and Hellenized Campania to the south-east. The river valley facilitated movement up into the Apennines, particularly commerce in salt from the coastal pans.9 Thus the city was locally well placed with regard to communications and trade. It was also on a cultural frontier between Etruscans, Faliscans and Latins. The local geology provided soft tufas for building and volcanic sands for mortars (DeLaine in this volume). The geologically ancient volcanoes close by in South Etruria and the Colli Albani, and the more recent eruptions further afield in Campania, ensure that not only the past but the present city is periodically rocked by earthquakes, as in AD 1980 (Fig. 1.2).10
Until the late 19th and early 20th century canalisation of the Tevere, the river dominated the life of the city, not least because of perennial flooding of the low-lying areas.11 The Campo Marzio (Campus Martius, Mezza Luna) was particularly vulnerable when the Apennine snows melted (Fig. 1.2). At this time the river increased its rate of flow in a comparatively straight stretch to the north, then turned virtually ninety degrees to the west to pass round the meander core. The weight of water would burst over the bank flooding the flat area south of the turn. These inundations caused destruction of buildings and the spread of disease...