Greek architecture

The architecture and urbanism of the Greeks and Romans were very different from those of the Egyptians or Persians in that civic life gained importance. During the time of the ancients, religious matters were the preserve of the ruling order alone; by the time of the Greeks, religious mystery had skipped the confines of the temple-palace compounds and was the subject of the people or polis. Greek civic life was sustained by new, open spaces called the agora which were surrounded by public buildings, stores and temples. The agora embodied the new found respect for social justice received through open debate rather than imperial mandate. Though divine wisdom still presided over human affairs, the living rituals of ancient civilizations had become inscribed in space, in the paths that wound towards the acropolis for example. Each place had its own nature, set within a world refracted through myth, thus temples were sited atop mountains all the better to touch the heavens.

Temple of Concordia in Agrigento, Sicily

The Romans conquered the Greek cities in Italy around three hundred years before Christ and much of the Western world after that. The Roman problem of rulership involved the unity of disparity — from Spanish to Greek, Macedonian to Carthaginian — Roman rule had extended itself across the breadth of the known world and the myriad pacified cultures forming this ecumene presented a new challenge for justice. One way to look at the unity of Roman architecture is through a new-found realisation of theory derived from practice, and embodied spatially. Civically we find this happening in the Roman forum (sibling of the Greek agora), where public participation is increasingly removed from the concrete performance of rituals and represented in the decor of the architecture. Thus we finally see the beginnings of the contemporary public square in the Forum Iulium, begun by Julius Caesar, where the buildings present themselves through their facades as representations within the space. As the Romans chose representations of sanctity over actual sacred spaces to participate in society, so the communicative nature of space was opened to human manipulation. None of which would have been possible without the advances of Roman engineering and construction or the newly found marble quarries which were the spoils of war; inventions like the arch and concrete gave a whole new form to Roman architecture, fluidly enclosing space in taut domes and colonnades, clothing the grounds for imperial rulership and civic order.
This was also a response to the changing social climate which demanded new buildings of increasing complexity — the coliseum, the residential block, bigger hospitals and academies. General civil construction such as roads and bridges began to be built.