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
After the Sack of Constantinople in 1204 during the Fourth Crusade, Pergamon became part of the Empire of Nicaea. When Emperor Theodore II Laskaris () 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. The monuments of the Attalids and the Romans were only plundered ruins by this time.