Pergamon extended down the South slope in the 3rd century B.C. and during the 2nd century a massive building program completely transformed the entire lower slope. The major construction in the area was the gigantic gymnasium complex which extended down three large terraces linked by vaulted stairways and passages. The complex encorporated three open training courts, a covered track or xystus, a small theater or odeum, several shrines, and two large baths. Other major sections of the middle city included the Sanctuary of Demeter and Kore and, below the gymnasium along the main street leading to the Eumenes' Gate, the lower agora. North and east of the gymnasium massive terraces support the streets and houses of the residential quarter. In the first half of the 2nd century B.C. Eumenes II strengthened the entire fortification system of Pergamon and enclosed all of the middle city, which extended almost to the base of the south slope, within the new walls.
During the Roman Imperial period the city continued to expand southward and spread over the plain and the area occuppied today by modern Bergama. The large Sanctuary of the Egyptian Gods (the "Kizil Avlu"), numerous bridges, and remains of the Roman stadium, theater, and amphitheater remain visible today.
During the reign Eumenes II (197-159 B.C.) Pergamon eached its peak. The kingdom had grown to include most of western Anatolia and was rich in agriculture and industry. Noted industrial exports included textiles, fine pottery, and "Pergamene paper" or parchment. The last industry developed when Ptolemy, reportedly jealous of the growing fame of the library in Pergamon, prohibited the export of papyrus from Egypt. The envied library possessed some 200,000 volumes. These later went to enrich Mark Antony's rival library in Alexandria. Pergamon rivalled Athens and Alexandria as centers of Hellenic culture. The city possessed one of the greatest libraries of antiquity, monumental gymnasia, and numerous religious sanctuaries, including the Asklepion outside the city walls. Pergamon was a haven for noted philosophers and artists and was the center of a major movement in Hellenistic sculpture. The Attalids supported the arts and learning in Pergamon and elsewhere and made major donations, such as the Stoa of Attalos II in Athens.
After a slight decline in the 1st century A.D. Pergamon went through a second period of greatness in the 2nd century A.D. New monumental structures were erected, including the large (ca. 300 x 100 m) sanctuary to the Egyptian gods in the center of the Roman city. The Sanctuary of Asklepios grew in fame and was considered one of the most famous therapeutic and healing center of the Roman world. Galen, after Hippocrates the most famous physician of antiquity, was born at Pergamon and received his early training at the Asklepion. By the end of the 2nd century A.D. Pergamon had become an important Christian center and the monumental Temple of Serapis in the sanctuary to the Egyptian gods was converted to a church. Weakening of the Pax Roma resulted in economical decline consequently Pergamon lost much of its importance. In Byzantine times A.D. 716 the city was sacked by the Arabs, another wall was built higher up the hill, enclosing a still smaller area, to provide protection against threatening Arab invasions followed by also the Seljuks. In the later centuries, Pergamon was occupied by the Ottomans, 14th century, and thereafter the city on the hill was abandoned and fell into decay, while the new town, Bergama grew up on the south side of the hill.
