During the Hellenistic period, it became the capital of the Kingdom of Pergamon in 281–133 BC under the Attalid dynasty, who transformed it into one of the major cultural centres of the Greek world.

[5] Settlement of Pergamon can be detected as far back as the Archaic period, thanks to modest archaeological finds, especially fragments of pottery imported from the west, particularly eastern Greece and Corinth, which date to the late 8th century BC.

[8] Xenophon, who calls the city Pergamos, handed over the rest of his Greek troops (some 5,000 men according to Diodorus) to Thibron, who was planning an expedition against the Persian satraps Tissaphernes and Pharnabazus, at this location in March 399 BC.

In the Roman–Seleucid War, Pergamon joined the Romans' coalition against Antiochus III, and was rewarded with almost all the former Seleucid domains in Asia Minor at the Peace of Apamea in 188 BC.

Eumenes II supported Rome again in the Third Macedonian War, but the Romans heard rumours of his conducting secret negotiations with their opponent Perseus of Macedon.

Despite this etymology, parchment had been used in Asia Minor long before the rise of the city; the story that it was invented by the Pergamenes, to circumvent the Ptolemies' monopoly on papyrus production, is not true.

The members of the Pergamene aristocracy, especially Diodorus Pasparus in the 70s BC, used their own possessions to maintain good relationships with Rome, by acting as donors for the development of the city.

Pliny the Elder refers to the city as the most important in the province[20] and the local aristocracy continued to reach the highest circles of power in the 1st century AD, like Aulus Julius Quadratus who was consul in 94 and 105.

[21] As a result of the ongoing Arab threat, the area of settlement retracted to the acropolis, which the Emperor Constans II (r. 641–668) fortified[21] with a 6-meter-thick (20 ft) wall built of spolia.

[22] When Emperor Theodore II Laskaris (r. 1254–1285) visited Pergamon in 1250, he was shown the house of Galen, but he saw that the theatre had been destroyed and, except for the walls which he paid some attention to, only the vaults over the Selinus seemed noteworthy to him.

[22] The Ottoman Sultan Murad III had two large alabaster urns transported from the ruins of Pergamon and placed on two sides of the nave in the Hagia Sophia in Istanbul.

[23] Pergamon, which traced its founding back to Telephus, the son of Heracles, is not mentioned in Greek myth or epic of the archaic or classical periods.

This material was dealt with in a number of tragedies, such as Aeschylus' Mysi, Sophocles' Aleadae, and Euripides' Telephus and Auge, but Pergamon does not seem to have played any role in any of them.

[37] In their constructive adaptation of the myth, the Attalids stood within the tradition of the other, older Hellenistic dynasties, who legitimized themselves through divine descent, and sought to increase their own prestige.

[39] In the late 18th century, these visits were reinforced by a scholarly (especially ancient historical) desire for research, epitomised by Marie-Gabriel-Florent-Auguste de Choiseul-Gouffier, a traveller in Asia Minor and French ambassador to the Sublime Porte in Istanbul from 1784 to 1791.

At the beginning of the 19th century, Charles Robert Cockerell produced a detailed account and Otto Magnus von Stackelberg made important sketches.

For the construction of the road from Pergamon to Dikili for which he had undertaken planning work and topographical studies, he returned in 1869 and began to focus intensively on the legacy of the city.

As a result of this short but intensive investigation, two fragments of a great frieze were discovered and transported to Berlin for detailed analysis, where they received some interest, but not a lot.

In 1971, after a short pause, Wolfgang Radt succeeded him as leader of excavations and directed the focus of research on the residential buildings of Pergamon, but also on technical issues, like the water management system of the city which supported a population of 200,000 at its height.

For the altar's construction, the required flat area was skillfully created through terracing, in order to allow it to be oriented in relation to the neighbouring Temple of Athena.

[54] At Pergamon, Dionysus had the epithet Kathegemon, 'the guide',[55] and was already worshiped in the last third of the 3rd century BC, when the Attalids made him the chief god of their dynasty.

A two-story stoa surrounding the temple on three sides was added under Eumenes II, along with the propylon in the southeast corner, which is now found, largely reconstructed, in the Pergamon Museum in Berlin.

The balustrade of the upper level of the north and east stoas was decorated with reliefs depicting weapons which commemorated Eumenes II's military victory.

The Temple of Hera sat in the middle of the upper terrace, facing to the south, with a 6-metre-wide (20 ft) exedra to the west and a building whose function is very unclear to the east.

In this place people with health problems could bathe in the water of the sacred spring, and in the patients' dreams Asclepius would appear in a vision to tell them how to cure their illness.

Galen, the most famous doctor in the ancient Roman Empire and personal physician of Emperor Marcus Aurelius, worked in the Asclepieion for many years.

An angry mob is said to have burned Saint Antipas alive in front of the Temple inside a brazen bull-like incense burner, which represented the bull god Apis.

Separate from this, a new area was laid out in Roman times, consisting of a whole new city west of the Selinus river, with all necessary infrastructure, including baths, theatres, stadiums, and sanctuaries.

[84] Because of significant new construction in the immediate vicinity – the renovation of the Sanctuary of Athena and the Pergamon altar and the redesign of the neighbouring area - the design and organisational principle of the Upper Agora underwent a further change.

The pipe consisted of three channels, which ended 3 km north of the citadel, before reaching the valley, and emptied into a pool, which included a double sedimentation tank.