The Gadara Aqueduct was a Roman aqueduct to supply water to the city of Gadara, modern-day Jordan, and the longest known tunnel of antiquity. The 170-km (105.6-mi) long pipeline was constructed in the qanat technology, that is as a series of well-like vertical shafts, which were connected underground from opposite sides by gently sloping tunnels. The longest section featured a length of 94 km (58.4 mi). Partly following the course of an older Hellenistic aqueduct, excavation work arguably started after a visit of emperor Hadrian in 129-130 AD. The Gadara Aqueduct was never quite finished, and was put in service only in sections. It was discovered and explored as late as 2004.
Mathias Döring: "Roman Water Systems in Northern Jordan", Proceedings of the 12th International Congress on the History of Water Management and Hydraulic Engineering in the Mediterranean Region (Ephesus, Okt. 2004), Österreichisches Archäologisches Institut, Sonderschriften, Vol. 42 (Leuven, 2006), pp. 237–243
Mathias Döring: "Wasser für Gadara. Römische Fernwasserleitung im Norden Jordaniens, Wasserwirtschaft, H. 8 (2007), pp. 21–25
Mathias Döring: "Qanat Firaun. 106 km langer unterirdischer Aquädukt im nordjordanischen Bergland, Schriften der Deutschen Wasserhistorischen Gesellschaft, Vol. 10 (2008), pp. 1–16
Mathias Döring: "Wasser für die Dekapolis. Römisches Wasserversorgungssystem im Norden Jordaniens", Schriften der Deutschen Wasserhistorischen Gesellschaft, Vol. 5, pp. 183–212