Roman aqueduct built in the 1st C. AD, it was designed to carry the water across the small Gardon river valley. It was part of a nearly 50 km (31 mi) aqueduct that brought water from the Fontaines d'Eure springs near Uzès to the Castellum in the Roman city of Nemausus (Nîmes).
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. The masonry was lifted into place by block and tackle with a massive human-powered treadmill providing the power for the winch. A complex scaffold was erected to support the aqueduct as it was being built. The face of the aqueduct still bears the mark of its construction, in the form of protruding scaffolding supports and ridges on the piers which supported the semicircular wooden frames on which the arches were constructed. It is believed to have taken about three years to build, employing between 800 and 1,000 workers. (Wikipedia)