We had a very good stay in Madrid, and Carlos's flat was the perfect base for exploring Madrid. Everything is walkable and if not, the metro is nearby. The flat is a cosy city place, we didn't need much as we were out most of the time. Carlos has left lots of information of places to eat and to visit, which we found really useful. Wifi seemed decent and the neighbourhood lively, and you're right opposite the mercado san fernando which had a great vibe.