Ghasabeh qanat is the biggest, deepest, most admired, and the oldest world’s qanat related to 2500 to 2700 years ago, one of the world’s hydro system masterpieces constituted of two major canals and six secondary branches. The number of wells in this qanat is more than 470 and its major well is located on the north hillside of Siahkuh in the depth of 280 to 300 meters. Naser Khosrow considered the depth of qanat well about 700 Guz (unit of measurement) and 4 Parasang (unit of measurement).
Now the charge of the qanat is about 150 liters per second and it is the only water source of the city. Ghasabeh qanat is one of the amazing human-made phenomena and the symbol of human harmony with nature. The qanat space adorned with a beautiful form by old architects. The interior space of the qanat has amazing tunnels and canals with some holes to put the oil lamps and lighting fixtures on them.
Discovered pieces of pottery around wellhead state that the Ghasabeh was located in the original canal of the original qanat at the time of the Achaemenids and it was followed by other wells in times of drought. The Gonadab Ghasbeh qanat is one of the best tourist sites of the city based on its position and antiquity.