Mmm the back door for the Gate is an alternative for invasion during siege ?
Not really, I just wanted to make some kind of a entrance to the castle. The way I did it before you couldn't get into the castle if you spawned outside of it.
Siege will go normally with ladders.
I left the opening because I imagined the Bloody Gate as
two tall towers connected with a covered bridge and huge battlements on each side, built into the mountain
The passage would be (in real life) easily deffended with smaller amount of solders then the attacker because it's narrow, and if the attack came from both sides, the attacker would still be under fire from 3 sides at once both in front and back.
The entrance in the castle lacks moats or anything like that, so i made a small entrance, again... to be easily defended. Like I said, I'm a reality freak.
That's why I sometimes dispair at the options of elements in the MB Editor, not really allot you can do with what is available. Especially Winterfell (with the snow and all). But we make due.