Chornedsnorkack is incorrect to say that all widebodies have two sidewalls and two aisles. The A380 has four sidewalls and three aisles.
Thanks for reminding, though it is 747 which has 4 sidewalls and 3 aisles. Mind you, it means that only 10 window and aisle seats combined, out of 16. Whereas A380 has 4 sidewalls and 4 aisles, so 12 window and aisle seats combined, out of 18. A380 and B747 have the same number of middle seats, and A380 has more window and aisle seats.