Hippodamus of Miletus is the leader and most famous city planner. Aristoteles is the best resource for us to learn about him. Aristoteles says these about him "long haired, extraordinary personality and has ideas about the ideal city". He had specially planed Athens (Piraeus).
The Greeks established new colonies between 6th and 5th Centuries BC. Also they rebuilt the cities those were destroyed during the wars against Persians. The architect Hippodamus developed new method according to the new needs. The plan was very simple and easy to apply. The streets would cut vertically with one another ninety degree angle. This plan was called "Grid" or "Check". This plan shape gave the possibility to the cities to expand in Hellenistic and Roman periods. Not only in flat land but also it could be applied on slopes with terracing system. The most wonderful examples of this plan are Priene and Pergamum. This rectangular plan leaded for building more modern architecture town planning. Before the cities were build unconsciously but Hippodamus took the major role to plan the cities and take them under control.
Piraeus, the most famous cities of the time was completely rebuilt by Hippodamus in symmetric. Streets intersecting each other in parallel and straight. Hippodamus rebuilt Miletus where he was born according to this plan. Then the plan was applied in Thurio and Rhodes in southern Italy.
According to Hippodamus, Agora was the first and the most important building in a city. As Agora was the life center of a city a few perpendicular blocks are left for it. After that gymnasium, stadium, theater and official buildings were located. Then the settled areas were located. There is no information about the separate settlements for aristocrats, soldiers and poor people. But the poor people were out of the city and far from these places. Underground sewage system was applied the entire city and there were drainpipes. They were built separately then the roads, streets and city walls. Main doors of City walls were open to an important street.
In square planed cities they were built in West - East, North - South directions and the Temples were built to East side of the city. Some of the cities built according to Hippodamus plan: Silenus in Sicily, Olynthus in Khalkidhiki, Priene, Miletus, Pergamum, Halicarnassus, Knidos, and Magnesia. The best visible sample is Priene. Alexander the Great and the following leaders took samples of Priene and Hippodamus plans while establishing in every new city.
Many US cities have been built with Hippodamus plan, including the New York.