Pergamon
Pergamon's other notable structure is the great temple of the Egyptian gods Isis and/or Serapis, known today as the "Red Basilica" (or "Kızıl Avlu" in Turkish), about south of the Acropolis at (39 7' 19" N, 27 11' 1" E). It consists of a main building and two round towers within an enormous "temenos" or sacred area. The temple towers flanking the main building had courtyards with pools used for ablutions at each end, flanked by stoas on three sides. The forecourt of the Temple of Isis/Sarapis is still supported by the Pergamon Bridge, the largest bridge substruction of antiquity.
Hellenistic period
After the death of Lysimachus, one of his officers, Philetaerus, took control of the city of Pergamum in 282 BC along with Lysimachus' war chest of 9,000 talents and declared himself loyal to Seleucus I while remaining de facto independent. His descendant, Attalus I, defeated the invading Galatians and proclaimed himself an independent king. Attalus I (241–197 BC), was a staunch ally of Rome against Philip V of Macedon during the first and second Macedonian Wars. For his support against the Seleucids in 190 BC, Eumenes II was rewarded with all the former Seleucid domains in Asia Minor. Eumenes II turned Pergamon into a centre of culture and science by establishing the library of Pergamum which was said to be second only to the library of Alexandria with 200,000 volumes according to Plutarch. It included a reading room and a collection of paintings. Eumenes II also constructed the Pergamum Altar with friezes depicting the Gigantomachy on the acropolis of the city. Pergamum was also a center of parchment ("charta pergamena") production. The Attalids ruled Pergamon until Attalus III bequeathed the kingdom to the Roman Republic in 133 BC to avoid a likely succession crisis.