If you’re in the Retiro area, perhaps on a Museum crawl or doing the tourist thang, punctuate the culture with a quick pit-stop; this is the ideal place to drink some wine, grab a bite and gather the strength to move on.
It's best on a sunny day, especially if you can find a spot on the terrace. If it's overcast, just grab yourself a glass of good Spanish wine and perch on one of the stools by the window for an excellent session of people watching.
The bar has a small cocktail list full of classics, but the place is better recognised for great wine and killer tapas by one of Spain's most famous chefs with links to the holy foodie grail, El Bulli. Serving modern up-market versions of old classics such as croquetas and patatas bravas, the food here is definitely worthy of an instagram or two.