I stayed at Mario's for two nights and really enjoyed my stay.
Prior to my arrival he made me feel very welcome already, without even having met him! Things like Wifi password, location and arrival time were settled within hours after booking. Very efficient!

Even though Mario was away on holiday during my stay, he was still easily reachable on Whatsapp.

The place itself is right in the heart of Madrid. It really cannot get more central. I would say it feels a bit more like a little hostel. Even though there were a couple of other visitors, the place was clean - a cleaner comes regularly.

The room was small and as others have pointed out, there is no window facing the outside, but only a window above the door, facing the hallway. I can imagine that it may get a bit stuffy in summer, although there is a fan provided. However, I slept there very comfortably.

For anyone who only stays in Madrid for a short while and will spend most of their time exploring the city, then this place is perfect, as it is great value for your money and centrally located, with all the sights in walking distance.

I would come back again! Thanks for having me Mario!