This article is an exercise in the historiography of ancient technical artefacts, beginning from the examination of a second-century a.d. cippus inscribed with the story of a Roman engineer, Nonius Datus, who designed and supervised the construction of an aqueduct in Algeria. The first section looks at the aqueduct from the point of view of the history of engineering. The second traces the history of the inscription as a document in the debate about imperialism and technology. In the third section, the focus is on what Datus himself was trying to communicate. The conclusion makes a case for considering ancient technical artefacts from multiple perspectives.