The streets of the city, built in the period up to the fourth century B.C. according to the principles of Hippodamus of Miletus, were laid out regularly in draughtboard pattern, pointing to the four cardinal points and crossing one another at right-angles. The main streets are 5-7 meters wide, the subsidiary streets are narrower (3,5-4,5 meters). Under these streets, which are paved with regular stones, is the drainage system. The pavements of this extremely clean city were well-paved, and the terraces, rising from south to north; were connected by steps. The blocks girded by these streets were about 35 by 47 metres. The houses cover an eighth of the area of these blocks.