Roads
Peoples had built roads long before Roman times: by the tenth century BC the Chinese had begun to construct roadways between their major cities, and during the fifth century BC the Persians built a similar network. But most of these early inter-city links were little more than tracks.
It was the Romans who built the first extensive system of paved roads: generally five to six metres (16 to 20 ft) wide and one to two metres (3 to 6 ft) deep, consisting of a base of gravel covered with closely fitted stone blocks. Unlike other peoples who built similar roads, the Romans did not follow the contours of the land but made their roads as straight as possible to facilitate communications and transportation, especially for military purposes.
Aqueducts
The amenities of urban life and the health of the people necessitated the provision of a dependable water supply to Rome and then later to cities throughout the empire. Rome itself had eleven aqueducts: Appia (312 BC), Anio Vetus (272 BC), Marcia (144 BC), Tepula (125 BC), Julia (33 BC), Virgo (19 BC), Alsietina (2 BC), Claudia (38), Novus (38), Traiana (109) and Alexandrina (226).
For most of their length the aqueducts operated by gravity alone. To cross a river, as at Nimes (France), or a valley, as at Segovia (Spain), a viaduct (bridge) was erected to maintain the gradient of the system; except if the drop exceeded fifty metres then an inverted syphoning system was employed where airtight lead pipes carried the water over the valley floor and the pressure of the descending water forced the water up the opposite hill join the continuation of the free flow channel where gravity took over again. Sand and other impurities were removed by settling tanks along the line.
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