Pont du Gard, France
The Pont du Gard is an aqueduct constructed by the Roman Empire. It is built on three levels, the Pont is 49 m high, and the longest level is 275 m long. On its first level it carries a road and at the top of the third level, a water conduit, which is 1.8 metres high and 1.2 meters wide and has a gradient of 0.4 percent. It was constructed entirely without the use of mortar. The aqueduct's stones, some of which weigh up to 6 tons, were precisely cut to fit perfectly together eliminating the need for mortar.