Derelict Roman Aqueduct 30 km north of Nikopolis, Epirus, Greece. Nikopolis was founded by Octavian Augustus following his victory over Mark Anthony and Cleopatra at the battle of Actium in 31 BC. The aqueduct was built after the founding of Nikopolis and took decades to complete, and created using tens of thousands of slaves. In total the aqueduct was part of a pipeline that stretched 50 km transporting water from the springs of Louros, to the two tanks of Nymphaeum of Nikopolis. In most of their aqueducts the Romans used to build a reservoir near the springs before they started transporting water in order to maintain a gradient of 1:1000, ensuring a constant flow and pressure. Aqueducts and viaducts were both developed by Roman engineers. The long spans of Roman viaducts were supported by semicircular arches resting on piers of stone or masonry.