Pergamon
Pergamon lies on the north edge of the Caicus plain in the historic region of Mysia in the northwest of Turkey. The Caicus river breaks through the surrounding mountains and hills at this point and flows in a wide arc to the southwest. At the foot of the mountain range to the north, between the rivers Selinus and Cetius, there is the massif of Pergamon which rises 335 metres above sea level. The site is only 26 km from the sea, but the Caicus plain is not open to the sea, since the way is blocked by the Karadağ massif. As a result, the area has a strongly inland character. In Hellenistic times, the town of Elaia at the mouth of the Caicus served as the port of Pergamon. The climate is Mediterranean with a dry period from May to August, as is common along the west coast of Asia Minor.
Pergamon
The Madradağ aqueduct was a ceramic pipe with a diameter of 18 cm which already brought water to the citadel from a source over 40 kilometres away in the Madradağ mountains at 1174 m above sea level in the Hellenistic period. Their significance for architectural history lies in the form of the last kilometres from the mountains through a 200 metre deep valley to the Akropolis. The pipe consisted of three channels, which ended 3 km north of the citadel, before reaching the valley, and emptied into a pool, which included a double sedimentation tank. This pool was 35 metres higher than the summit of the citadel. The pipe from the pool to the Acropolis consisted of only a single channel - a lead pipe pressurised to 200 mH2O. The water was able to cross the valley between the pool and the citadel with the help of this pressurised conduit. It functioned as a communicating vessel, such that the water rose to the height of the citadel on its own as a result of the pressurised pipe.