Carlos is building three gardens, each the same size, in his backyard. Each garden is in the shape of a square with a 3-foot by 3-foot section removed from each of the four corners. One garden is shown below. A square with sides lengths of 16 feet. 3 by 3 feet squares are cut out of each corner of the larger square.

What is the total area of all three gardens?
220 feet squared
256 feet squared
660 feet squared
768 feet squared