inaccessable area?

Don't know if this is possible or not i cant seem to find a way into the iron citadel area. I have cleared every single map on the outside into the area where the citadel is. 1 map i cant see i have cleared just unsure if their is parts of the atlas that is totally impossible to get to. i think i have moused over every most pixels on the way in i cant find a way. the invisible map looks like the way into the citadel just cant open any maps on the inside. thanks