the task of protecting the city against other european nations, as well as pirates and privateers, was made slightly easier by the geographical terrain, specifically by the mountains and hills surrounding the bay, however, military intervention was soon necessary.

the resulting fortification and defense of the area, lasting the following five hundred years, is evidenced by rio's and nearby niterói's historic forts. 

among them, fortaleza de santa cruz stands out, along with the forte de são luiz and forte forte do pico, as well as,  of course, the forte de copacabanaeasily accessible at the beach, and the fortaleza de são joão, home to the very spot, where the city was founded.