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.
Pergamon
The earliest mention of Pergamon in literary sources comes from Xenophon's Anabasis, since the march of the Ten Thousand under Xenophon's command ended at Pergamon in 400/399 BC. 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. At this time Pergamon was in the possession of the family of Gongylos from Eretria, a Greek favourable to the Achaemenid Empire who had taken refuge in Asia Minor and obtained the territory of Pergamon from Xerxes I, and Xenophon was hosted by his widow Hellas.