The Spanish crown was looking for different ways of defend its sea borders against other powerful nations, while struggling to maintain its domination in the Americas. Together with the Spanish fleet (“La Flota”) protecting the entry from the sea, important ports of the New World (Vera Cruz, Puerto Rico, Santo Domingo, Havana, Cartagena die Indias, Panama, & Montevideo) have became fortified cities of the colonized world. During the last couple of years of Spanish domination in South America, the city of Maldonado, its bay and its port have been the most important example of the engineering that was geared for military defense. 200 years later, “A Bay to Defend” narrates us one of the richest aspects of the cultural patrimony and the history of the Gorriti Island and the Bay of Maldonado. Interviews, abundant use of archived images, graphics and 3D animations, the documentary re- creates the history of fortified castles of the coast of Maldonado, its Geo-political importance and the process of their recovery and conservation.