The host, the host, the host. Alfonso is a 5 star host. Chill, friendly, knowledgeable, and most of all available. He knows Madrid like the back of his hand and loves it with his whole heart. He is an amazing human.
The apartment is great, beautiful, and quiet. The room is small but nice. The bathroom is great, and you have a nice kitchen and washing machine.
And finally: the location. You can’t dream better. You are in a capital, but you won’t have to use the metro that much with such a location.
100% recommended, I won’t stay anywhere else if I come back to Madrid.