Aqueducts are very impressive examples of the art of construction in the Roman Empire. Even today, they still provide new insights into aesthetic, practical and technical aspects of construction and use. Scientists at Johannes Gutenberg University Mainz (JGU) investigated the longest aqueduct of the time, the 426-kilometer-long Aqueduct of Valens supplying Constantinople, and revealed new insights into how this structure was maintained. It appears that the channels had been cleaned of carbonate deposits just a few decades before the site was abandoned.