OK, so before you shake your head in disgust at our apparent perverseness, please give us a chance to explain ourselves. Out in the barrio of Vallecas is a park that's been nicknamed Parque de las Siete Tetas after the similarity in shape of its seven round hills to *ahem* breasts. It's a hidden spot for spectacular views of the Madrid skyline that isn't in the guidebooks. In fact many madrilenos don't even know about it (no, we're not making it up)! Word of advice - if you can't find the park, ask a local in Vallecas for "Parque de las Siete Tetas" instead of the official name of "Cerro del Tio Pio". The latter will get you a blank expression; the former will get you a smirk and a point in the right direction.
We think Trabblrs will love spending an afternoon or evening at the park. Have a picnic, play cards, throw a frisbee, drink wine. This is truly a unique place in Madrid where you can get away from the city without having to leave it. Close by is El Mirador de Vallecas where you can enjoy a cocktail while watching the sun go down.
Meeting point: Outside the Museo Municipal de Bomberos (Firefighters Museum) on Calle Boada. The park is right behind it. The closest Metro stop is Buenos Aires on the Blue / 1 Line.
Leaders, sunsets from here awesome (hint, hint). El Mirador may be closed in the winter, but it's open from 5:00pm onwards during the summer on Sundays through Thursdays and 12:00pm onwards on Fridays and Saturdays.