This article investigates the relationships between hydraulic engineering and antiquarian studies in Rome in the long decade between the devastating Tiber River flood of 1557 and the completion of the repair of an ancient aqueduct, the Acqua Vergine, in 1570. The essay focuses on the physician Andrea Bacci (1524-1600), the engineer Antonio Trevisi (d. 1566), the jurist and Roman magistrate Luca Peto (1512-81), and the antiquarian Pirro Ligorio (ca. 1510-83). These individuals from both learned and practical backgrounds approached urgent problems of hydraulic engineering by studying ancient texts and artifacts, and they proposed solutions that were influenced by their study. This confluence of antiquarian study and engineering contributed to the development of empirical methodologies in the late Renaissance by making engineering part of a learned discourse.