Trending Stores: Adidas has opened its largest store in the world — a 45,000-sq.-ft., four-story flagship on Fifth Avenue in New York City. Sleek and ultra-modern with industrial accents, the store marks the debut of the athletic giant’s stadium retail concept, a format inspired by high school stadiums. It features high-school reminiscent bleacher stands for live-game viewing on big screens, locker room-style dressing rooms, and track and turf sections where customers can try out products.