im not sure the proper name for the icing. my family has all ways just called it whipped icing. its not super surgery like butter cream its fluffy and smooth. i dont like the taste of fondant, so it would have to be made with the whipped icing.
i read a post that was asking about how to do it with fondant and a few suggested using a texture sheet on the fondant http://www.globalsugarart.com/product.php?id=20402&name=Cobblestone%20Texture%20Sheet%20by%20CK. i might be able to get a similar effect if i just drew the lines myself with something like a tooth pick. but how do i get the color right? you look at castle walls and they are a mix of blended colors. im looking to get a color similar to this http://farm1.static.flickr.com/107/282552057_d52776cfe4.jpg i know this is made with fondant but this is kind of the color of how i want my walls to turn out.

Whipped icing can be hard to color not to mention that it doesn't crust at all so using the textured mat won't work given that you need either fondant or a crusting buttercream to be able to successfully apply it. Also, whipped icing can be temperamental when you mess with it too much so this would make coloring it more difficult. You can maybe try airbrushing the colors onto the icing but as for getting the block look, I'd say manualy marking each block with a toothpick (or maybe even using a small square/rectangle cookie cutter) would be your only real option. HTH,
Fedra

thank you for your reply fedra but is there anything else i could do besides airbrushing it? i googled airbrush for icing and this was the cheapest one i could find. http://www.amazon.com/dp/B004L08MF0/?tag=cakecentral-20
i have never used one before and no one i know has ever used one before either so i dont think id be able to get the effect i want on the first try, and i dont want to be wasting cakes and icings just to get the effect i want and than this would be really the only time i would use the air brush so i think it would be a bit of a waste of money.

I don't think the look you want can be accomplished with whipped cream frosting.

You could separate your frosting into 3-4 batches, color each one a slightly different shade of grey/brown, and load 4 different piping bags, and pipe blobs of frosting one at a time onto your cake. But it's still not going to look like the cakes in those photos... best of luck.