Alberto's place is a small, top-floor flat with the main bed and a reclining area in the attic space. It is completely self-contained with cooker, television, Wifi, shower fridge/freezer, washing machine. It is a very small space but comfortable. The apartment is the only property on the top floor of the building and I often worked with the front door open to allow the light from the skylight to fill the area and hear the murmur of the street below.
The location is extremely central to Madrid. It is a couple of minutes to Cava Baja, Plaza Mayor, St Miguel food market, the Cathedral / Palace and 5 minutes from Sol. You could not really hope for a more convenient location to stay in central Madrid.
Alberto was easily contacted and always very willing to help - a couple of times the Wifi was playing up and it was resolved within minutes. He was also there to welcome me on arrival and had provided some wine and a snack for me when I arrived.
There are plenty of places nearby for coffee, shopping and eating. There are several supermarkets nearby.
Overall, I had a great time in Madrid and would recommend it for a trip. The only point to be aware of is the small size of the flat and the access to the sleeping area would be a problem for people with difficulty with mobility. Alberto's photographs make this clear.
In addition - it was a pleasure to get to meet Alberto and his wife, Consuelo. Both very friendly, approachable and generous people.