I stayed for a couple of days at Sergio's flat in the Lavapies neighborhood. The place is a cozy studio at the top floor of the building. The neighborhood is very multicultural and you really feel like a local wandering around the bars and shops. I very much enjoyed the area and I think it's probably one of the most underrated places in Madrid.
Sergio kindly waited until my late arrival and was quite flexible with all routine matters. Great Madrid experience !