The colossal cornerstones of commerce. Oversized outfitters. Merchandise Moguls. Mega Stores are giant facilities engineered to keep up with America's supersized habits. They are the largest, busiest places in the country. Their greatest challenge: keeping up with demand on a massive scale, and to do it, they have everything from scuba divers to sandblasters. It's not what's on the shelves--it's what happens behind the scenes.