The Gadara Aqueduct, also called Qanatir Fir'awn or Qanat Fir'aun (Pharaoh's Watercourse), was a Roman aqueduct supplying water for some of the cities of the Decapolis. It serviced Adraha (known today as Dera'a in Syria), Abila (at Wadi Queilebh in Jordan), and Gadara (modern-day Umm Qais in Jordan). The aqueduct has the longest known tunnel of the Classical era.