We had a great time at Carlos' apartment. Carlos was very attentive, showed us around and explained how everything worked. He left us a few supplies, like coffee and beer. He had several guides to Madrid, which was helpful, and gave us his phone number in case of any doubts, and answered our messages very quickly.
The apartment was very nice and spacious, had everything we needed. The roof top was a great addition, perfect for relaxing after a lot of walking around in the city. The subway was less than 10 min away, a light walk up the street. We really enjoyed our stay and would definitely stay there again at another opportunity!