ABSTRACT
The architectural climate in Rome changed abruptly after the death of Augustus in AD 14. The Temple of Concord, finished in AD 10, was to be the last great marble building of its kind built in Rome for some time. With the accession of Tiberius architectural fashion swung away from public monuments employing columnar orders. Instead the Emperor built a number of lavish residences for himself both in Rome and outside. Often sited in rocky or almost inaccessible locations they stimulated a renewed interest in concrete as a building material. For example, the Emperor's main residence for many years, the Villa Jovis at Capri, was perched on the top of a sheer cliff at one end of the island. Its location required the construction of enormous concrete water cisterns to store any rain that fell, and concrete buttresses were needed to stabilize the huge semicircular dining room with its dizzy panorama over the Gulf of Naples. Concrete undercrofting was also required to provide a flat platform for the large new palace he built for himself on the Palatine. The reign of Caligula (AD 37-41), too, was notorious for its architectural follies, for example the floating palaces he built for himself on Lake Nemi. One might have expected that an antiquarian like Claudius (AD 41-54) would have returned to Augustan propriety, but the architecture of the Claudian period has many odd features. His reign is notable for several heavily rusticated, stone buildings such as the Porta Maggiore, as well as a number of severely practical projects, such as the harbour at Ostia and two new aqueducts. This interest in engineering and the exploitation of concrete as a constructional medium continued into the reign of Nero (AD 54-68). In the latter part of Nero's reign the great fire destroyed much of the city of Rome. The rebuilding was done very largely in brick-faced concrete, and the new building codes, which laid down standards for new houses, are strikingly reminiscent of the Act of 1667 after the Great Fire of London. Nero's reign is memorable for the infamous Golden House, but this architectural extravaganza was in fact an extraordinarily important building. It represented a revolutionary departure in the exploitation of concrete as a building material. Terms like 'the new architecture' are
commonly applied to it. The architects of the Golden House began to realize the potential of concrete in shaping architectural space. Concrete was not just used as a medium to create coffered barrel vaults, but to mould apses, niches and domes, to open up and to enclose vistas, to provide hidden lighting effects, to shape an interior from the inside rather than the outside. To use Ward Perkins' words, 'the emphasis has suddenly shifted from the solids to the voids'. Thus the reign of Nero began an architectural revolution which was to gather pace over the next 70 years, until by the time of Hadrian the concept of interior space had changed beyond recognition.
