Pergamon
Pergamon lies on the north edge of the Caicus plain in the historic region of Mysia in the northwest of Turkey. The Caicus river breaks through the surrounding mountains and hills at this point and flows in a wide arc to the southwest. At the foot of the mountain range to the north, between the rivers Selinus and Cetius, there is the massif of Pergamon which rises 335 metres above sea level. The site is only 26 km from the sea, but the Caicus plain is not open to the sea, since the way is blocked by the Karadağ massif. As a result, the area has a strongly inland character. In Hellenistic times, the town of Elaia at the mouth of the Caicus served as the port of Pergamon. The climate is Mediterranean with a dry period from May to August, as is common along the west coast of Asia Minor.
Pergamon
Pergamon is a good example of a city that expanded in a planned and controlled manner. 
Philetairos transformed Pergamon from an archaic settlement into a fortified city. He or his successor Attalos I built a wall around the whole upper city, including the plateau to the south, the upper agora and some of the housing - further housing must have been found outside these walls. Because of the growth of the city, the streets were expanded and the city was monumentalised.
Under Attalos I some minor changes were made to the city of Philetairos.
During the reign of Eumenes II and Attalos II, there was a substantial expansion of the city. A new street network was created and a new city wall with a monumental gatehouse south of the Acropolis called the Gate of Eumenes. The wall, with numerous gates, now surrounded the entire hill, not just the upper city and the flat area to the southwest, all the way to the Selinus river. Numerous public buildings were constructed, as well as a new marketplace south of the acropolis and a new gymnasion in the east. The southeast slope and the whole western slope of the hill were now settled and opened up by streets.