As part of its mission to study and preserve Alexandria’s heritage, the CEAlex was requested by the Egyptian antiquities service to undertake a project of study, conservation and development of one of the most striking cisterns of the city, El-Nabih. In 1914, Evaristo Breccia wrote, “Today, because of the innumerable new constructions, the majority of the cisterns have disappeared, but several still exist and the Antiquities Service has managed to save one of three storeys. The Nabih Cistern, open to the public, is situated in the eastern part of the gardens on rue d’Allemagne”. This sad observation well illustrates just how singular is the fate of this cistern. An examination of the documentary resources shows how this structure – anonymous among the hundreds of others at the end of the 19th century – became, in less than a quarter of a century, one of the last visible signs of the ancient water supply infrastructure of Alexandria. An analysis of data from the site and the results of an initial excavation provided precise information as to the architecture and functioning of this remarkable monument.