Great Enclosure view (IMAGE) Aarhus University Caption The ruins of the ancient city of Great Zimbabwe. The vegetation around the ruins hides a lot of depressions, so-called Dhaka pits, which until now have been thought to have originated from the excavation of clay. With remote sensing methods and excavations, the researchers have found that the pits must also have been used to store and manage water for the city Credit Federica Sulas, Cambridge University Usage Restrictions Credit must be given to the creator. Only noncommercial uses of the work are permitted. License CC BY-NC Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.