As large as a castle yet lighter than air 100 men and their horses cannot move it what are you?

The Answer for the horse isle riddle question is "the castle's shadow". you must type it EXACTLY like this or you will not get it right. *withought the qoutation marks around it* NightWish from Roan server and on hi2. NO it is not! i tried it and it wasnt correct! u are not correct!