SPAIN, Segovia: This aqueduct, is a water-conveyance structure built under the Roman emperor Trajan (reigned 98–117 CE) and still in use. One of the best-preserved Roman engineering works, it was built of some 24,000 dark-colored granite blocks without the use of mortar. The aboveground portion is 2,388 feet long with 165 arches more than 30 feet high. In the center, the structure stands 93.5 feet above ground level. The aqueduct was designated part of the Segovia World Heritage site in 1985.