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Roman Eifel Aqueduct

The Roman Eifel Aqueduct once supplied the Roman city of Colonia Claudia Ara Agrippinensium, modern-day Cologne, with fresh drinking water. As one of the longest aqueducts of the Roman Empire and the largest ancient structure north of the Alps, it was built by the Romans.
History+
Around 80 AD, the Eifel Aqueduct was constructed in the northern Eifel region from Opus caementitium and masonry. It is believed that the Roman army was responsible for its construction, as only they possessed the necessary resources.
Source: Wikipedia · Licence: CC BY-SA 4.0
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 50.5472, 6.6423