it was originally  called the forte do vigia (fort of the watch), since its purpose was to observe the sea traffic on the baía da guanabara (guanabara bay).  the fort however, was popularly known as the forte do espia (fort of the spy). during this period it protected the city of rio de janeiro from invasion on several occasions.

approximately one hundred years later it was renamed the forte do leme, after the neighborhood where it is located.  in 1935, president getúlio vargas renamed it the forte duque de caxias, its present, official name.