The city was one of the fundamental institutions of the ancient world and as such was not confined to the civilisations of Greece and Rome. The city was synonymous with civilisation and in opposition to barbarity and chaos. Furthermore, the city was the agency through which the Graeco-Roman way of life was disseminated throughout the Mediterranean, Europe and the Near East. The criteria which defined a city in the eyes of the Greeks and Romans differed. The city was essentially a community of citizens, sharing common political, religious and social traditions. Within the Graeco-Roman world the city fulfilled various functions, and these functions affected its physical and architectural development. The political, economic, social and religious functions of the city are reflected in its public buildings and their location within the urban environment. The political and administrative role of the city is witnessed most of all in the agora and forum.