The Temple of Hylia has two exterior doors, one in the front and one on the side wall. The front door unlocks when the plot says you're supposed to go through it, but the other door never got unlocked during my playthrough. The map initially depicts both doors using the same "locked" icon, and there appears to be a path on the other side of the side door, so it seems like there ought to be a way to go through it.
So, is there a way to unlock it, or is it just there for decoration?