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.