While Fortnum and Mason was pretty, it was nothing compared to Harrod's - whose food halls rivaled those in Japanese department stores. They were amazing! There are 4 halls total -- 1) Prepared foods with a few mid-range counter restaurants (dim sum, sushi, and tapas); 2) Coffees, teas, biscuits, etc. 3) Fresh produce, butchers, seafood, poultry; and 4) Candy and the casual eateries - pizza, gelato, deli.
Not only are the halls themselves beautiful, with lovely mosaics, chandeliers, etc. the food is also artfully presented. These pictures don't do it justice, but here you go.