The Romans built hundreds of bridges and conduits to deliver water via gravity across their empire, and many of these marvels of civil engineering still remain in varying conditions.

See more photography in the Ancient Aqueducts gallery and Aqueducts group.

Photos from dkilim, Goutkin, mathrong, sebastien.barre, questforfire2010, temte_mc, Le Monde1, -keka-, jacqueline_poggi, calafellvalo, urban_lenny, and nkarabiber.