Perched atop the landmark Casino de Madrid building, this temple of haute cuisine is overseen, albeit from afar, by Ferran Adrià (Spain’s premier celebrity chef), but is mostly in the hands of his acolyte Paco Roncero. It’s all about culinary experimentation and a menu that changes with each new idea that emerges from the laboratory and into the kitchen. Other celebrity chefs occasionally make an appearance. You may not eat here often, but doing so just once will leave you in raptures.