Sobrino de Botín

The world's oldest continuously operating restaurant according to Guinness World Records — open since 1725, with a wood-fired oven that's never gone cold, still turning out cochinillo (roast suckling pig) the same way it has for three centuries.

The oven and dining rooms are original — ask to see the 300-year-old wood oven in the basement if the staff aren't already showing it off. Book ahead for dinner, especially weekends; the ground-floor rooms are the atmospheric ones, so specify a preference when reserving. Hemingway namechecked it in The Sun Also Rises, and the restaurant leans into that history without becoming a parody of itself.