Designed by the Greek engineer Eupalinus, the Samos structure ran mostly underground. The tunnel was approximately 1 mile long and almost eight feet in diameter. The water flowed through clay pipes that were laid inside the tunnel (Grolier, 1993). .
"The most famous aqueduct builders of ancient times were the Romans" (McDonald, 1998). Roman engineers built the main part of their aqueduct system at or below ground level. The water was carried through free flowing conduits. When the aqueducts needed to cross a valley or decent to a plane, the Romans built massive arched bridges. For some of the bridges, they had to build two or sometimes even three tiers of arches to get the height needed to keep an even flow. The bridges were a lot harder to build and took a lot more maintenance, than the ground level and underground level of the aqueducts (McDonald, 1998).
Rome's water supply came from 11 major aqueducts. Totaling 298 miles, they were built over a period of 500 years. The first was Aqua Appia, which was built in 312 BC. It was 10 miles long and only approximately 7 feet of it ran above ground. In 140 BC, the Aqua Marcia was built. It was the first "long" above ground aqueduct, and was built completely out of stone. "By 125 BC, when the Aqua Tepula was built, poured concrete had become the basic building material" (Grolier, 1993). At that time, underground pipes were being made of stone, clay, wood, and even lead (Grolier, 1993). .
Aqueducts were built in many areas of the Roman empire. "Remains of these aqueducts still exist. A few of them, such as the one at Segovia, Spain, have remained in use" (McDonald, 1998). Shown in Figure 1, is the Roman aqueduct in Segovia, Spain. At a height of 128 feet, the aqueduct was constructed from granite. It is a fine example of dry masonry. Figure 2 shows one of the most remarkable old roman aqueducts, the Pont du Gard near Nimes, France.