Most definitely a place that should be part of any Madrid visit. Located at the top of a beautiful Art Deco gallery in one of the prettiest areas in the city, this rooftop terrace offers some of the best views in town. There's a 3€ fee to ride the lift up, but the 360° superb views of the city's skyline are priceless. There's a chill-out area decked out with sunbeds, a bar style snacking area as well as a restaurant, all of them open all year round.
Start off with a glass of Cava (Catalán D.O. bubbly) or ask the bar staff to craft an amazing G&T - Spain's national drink (I know it isn't, but nobody does them like Spaniards do). Finding a shady spot can make all the difference between having a great time or spontaneously combusting, but you might have to wait a while as some people are engaging in the mother of all Spanish traditions - the siesta. So if they're ugly make some noise to make them move and if they're gorgeous buy them a drink and you might get invited to join them in the shade - otherwise enjoy a complementary tanning session with your beverage.
The service is excellent, very attentive. The restaurant serves food inspired by street markets from all over the world and is well worth the visit, booking is recommended.