+IMPERIAL ARCHITECTURE; AUGUSTAN AGE.+ Even in the temples of Greek style Roman conceptions of plan and composition are dominant. The Greek architect was not free to reproduce textually Greek designs or details, however strongly he might impress with the Greek character whatever he touched. The demands of imperial splendor and the building of great edifices of varied form and complex structure, like the thermæ and amphitheatres, called for new adaptations and combinations of planning and engineering. The reign of Augustus (27 B.C.-14 A.D.) inaugurated the imperial epoch, but many works erected before and after his reign properly belong to the Augustan age by right of style. In general, we find in the works of this period the happiest combination of Greek refinement with Roman splendor. It was in this period that Rome first assumed the aspect of an opulent and splendid metropolis, though the way had been prepared for this by the regularization and adornment of the Roman Forum and the erection of many temples, basilicas, fora, arches, and theatres during the generation preceding the accession of Augustus. His reign saw the inception or completion of the portico of Octavia, the Augustan forum, the Septa Julia, the first Pantheon, the adjoining Thermæ of Agrippa, the theatre of Marcellus, the first of the imperial palaces on the Palatine, and a long list of temples, including those of the Dioscuri (Castor and Pollux), of Mars Ultor, of Jupiter Tonans on the Capitol, and others in the provinces; besides colonnades, statues, arches, and other embellishments almost without number. +LATER IMPERIAL WORKS.+ With the successors of Augustus splendor increased to almost fabulous limits, as, for instance, in the vast extent and the prodigality of ivory and gold in the famous Golden House of Nero. After the great fire in Rome, presumably kindled by the agents of this emperor, a more regular and monumental system of street-planning and building was introduced, and the first municipal building-law was decreed by him. To the reign of Vespasian (68-79 A.D.) we owe the rebuilding in Roman style and with the Corinthian order of the temple of Jupiter Capitolinus, the Baths of Titus, and the beginning of the Flavian amphitheatre or Colosseum. The two last-named edifices both stood on the site of Nero’s Golden House, of which the greater part was demolished to make way for them. During the last years of the first century the arch of Titus was erected, the Colosseum finished, amphitheatres built at Verona, Pola, Reggio, Tusculum, Nîmes (France), Constantine (Algiers), Pompeii and Herculanum (these last two cities and Stabiæ rebuilt after the earthquake of 63 A.D.), and arches, bridges, and temples erected all over the Roman world.