One way to attack a castle was to surround it and lay siege to it, allowing no one in or out. The hope was that the people in the castle would eventually starve to the point they would give up. To prepare for this, a castle had a large store room full of food.
Big rooms
It is impossible to tell.
It is in the secret store room behind the filing cabinet in the detention room on Big Nate Island. You need the blue prints from Nate's locker in order to access the secret room.
you need the gold gauntlets which can be found inside ganon's castle (but you need the 6 sages to actually get into the castle).
Ripley castle is big!
You can find this guy on the second floor of Falador Castle, the guy sitting down in a big room.
Maiden Castle is around 67 acres big
It depends on the castle.
It depends how big the castle was.
a big one
72 inches is 6 feet so you'd need about an 8 foot room or more
very big