yeah, but as writers we try to strike some kind of balance between real and ideal, eh? i doubt, though i can't actually verify this through experience, ivy is strong enough to support a man's weight as he's scaling a thirty foot wall. maybe if there's a trellis, but even then that's going to be one sturdy piece of decoration/plant support. climbing ivy would be suicide. i'm sure most lords would rather have that soldier working in the undermines (the method of tunneling used to collapse walls) than scaling walls, which were typically breached with siege machines taller than the wall (forget the name of these things off-hand).
your city most likely won't be entirely walled. 1,200 feet of palisade, i think, is considered very impressive, sans magick, of course. your 'suburbs' might have been protected by ringworks, but if you look at pictures of 'castles' (that is if your definition includes, too, the curtain wall, which typically is the case), you'll quickly see there's simply no room for a large population to live actually *inside* the 'castle' beyond a siege situation.
there's not likely to be much of a surrounding forest close by, either, unless the castle is very old. construction of the castles would have raped the woods for timber, which even for a stone castle required tremendous quantities. say it takes an average of seven to ten years to build a truly impressive structure, and that's not really a long time to completely replenish a forest with sizable trees. besides, though i'm hardly a historian, i can't think of any real castle whose nearest forest was close to arrow range.
basically, a 'castle' was for the lord, his family, and servants/garrison. inside the defensive walls you might find blacksmiths, the chapel and cobblers and such, but 'castles' weren't for the common folk to live in. those people lived in surrounding peasant villages, not necessarily right outside the foot of the wall, but not inside, either, lol. (i feel encouraged to put 'castle' in quotes, as the term typically takes on a synonomous meaning between the castle, the main living residence, and the battlements, which later came to be a supporting feature of the residence and kind of thrown in there, too, which i suppose is technically correct.)
i'm not too familiar with 'town walls' surrounding and protecting the outlying village other than ringworks, though i suppose it's likely some places had some kind of timber barricade. i'd imagine that that would be rather impractical to build and maintain when wood rot was a pretty serious issue and unless you're starting to get practically into a motte and bailey-type of thing connected with tall timbers, i can't see there being a tremendous defensive advantage there. surrounding an entire town with stone would be practically pointless unless it was high, and few lords would put the money into that structure when that's half the point of having a 'castle' in the first place, eh?
the point is not creating a strictly historically accurate castle, just not an overly romanticized one, either. i mean, clearly some of these writers have not done a lick of research. surrounding three square miles with forty foot high walls ain't gonna happen unless magick is involved, lol. it took roughly 2,000 workers and skilled labourers a year to add ten foot of heighth to an average castle wall, that's if everything went okay and you're not working on that castle that after 45 years *still* wasn't finished.
i can buy into it from a high fantasy standpoint, at least up to a certain point. that's where people sometimes seem to get confused or only see one view. that's also why i liked the LOTR movies that depicted theodin's (? and sp) 'castle' as being separated from the peasant village, while a lot of writer's just see the attacked castle on the side of the mountain as being the norm. fantasy or not, there's research involved, right? of course, people can't help but to write about kings, either, while on the other side of the haunted forest lies *another* king. ah, doubtful. warlords, maybe... kings, though?
a writer who has no historical background whatsoever writing about castles, kings, and the lives and mien of those people living in those places just comes off as crude and lazy to me. worse, highly romanticized and purply prosed doesn't have the effect of deflecting the lack of research. if your castle has 100 foot high white walls, fine... as long as that castle isn't impregnable because of just that. that could just be more wall that falls when you apply fire to crack it open like a walnut, heh heh. to be quite frank, if you can't google 'castle', maybe you don't have much business writing about them, eh? 'people in the background milling about, going about their business,' just doesn't cut it for me on any level, even for a short story. good lawd, at least throw a damn baker in there, will ya?