Ancient Greece encompassed the southern part of the Balkan peninsula and the Peloponnese, as well as the numerous islands of the Aegean Sea and the more remote islands of Crete and Cyprus. Moreover, Greek cities were founded along the adjacent coast of Asia Minor, in modern Turkey, during the early part of the first millennium bc. Finally, during the colonisation period starting in the second half of the eighth century bc, Greek settlements sprang up all round the Mediterranean and to some extent even on the Black Sea. This far-flung urban construction constituted the most important transformation of the landscape in the ancient world, and the one with the most lasting consequences.

Both geographical and political factors were decisive in the emergence of this Greek world. The landscape of Greece itself, with its small-scale structures, has only a few broad coastal strips and fertile plains, but many promontories and offshore islands.