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 Bridge
For urban development, such substructions are regarded as particularly useful for providing large open spaces in densely populated inner city areas. This was also the case in Pergamon, as the building of the Serapis Temple required the bridging of an entire section of the River Selinus in order to create sufficient space for a large platform in front of the temple.