This study focuses on the Spanish colonial watchtowers built by Augustinian friar, Julian Bermejo, on the southeastern Cebu Island, Philippines, as part of an elaborate plan to protect native settlements against Muslim marauders. These are slowly disappearing due to neglect and continuous exposure to natural hazards. Studies on these buildings are lacking and graphical records of their original constructions are scarce. In this regard, this research aims to define Bermejo’s defense model, clarify the watchtowers’ architectural characteristics and construction technologies, as well as establish their most common architectural types through data gathering from extant historical records and extensive field documentation.