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 Altar
The altar lost its function at the latest in Late Antiquity, when Christianity replaced and suppressed polytheistic religions. In the 7th century the acropolis of Pergamon was strongly fortified as a defense against the Arabs. In the process the Pergamon Altar, among other structures, was partially destroyed in order to reuse the building material. The city was nevertheless defeated in 716 by the Arabs, who temporarily occupied it before abandoning it as unimportant. It was only resettled in the 12th century. In the 13th century Pergamon fell to the Turks.