The roman aqueduct can be visited
Ancient BuildingCologne (Köln)
Roman Eifel Aqueduct

The Roman Eifel Aqueduct, also known as the Roman Canal, was a structure of antiquity and one of the longest aqueducts in the entire Roman Empire. It supplied the Roman city of Cologne with spring water from the Eifel.
History+
Around 80 AD, the Eifel Aqueduct was constructed in the Northern Eifel from opus caementitium and masonry. It replaced an older aqueduct, the so-called Vorgebirge Aqueduct, which had already been built around 30 AD and used water from sources in the Ville.
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: 50.9049, 6.9096