The middle of the three doors on the southern-facing wall of the Batería's citadel leads to what is also clearly a powder magazine. How many powder magazines does a relatively small battery of guns need? One imagines that outposts of Spain's far-flung possessions received supplies only sporadically, and there was thus a need to stack 'em high when they could. Clearly, it's been a while since the Spanish supply ship visited the Batería.