Three adults stayed in the apartment and it was excellent. Very central and convenient to everything we wanted to see, all the art galleries, central Madrid etc. whilst the apartment was not huge for three, it was quite satisfactory and very good value for money. It was clean and modern and the washing machine is a real plus. Helios was very helpful, and helped me arrange with the hotel on the corner for my lost luggage to be delivered there. When it arrived he brought it to the apartment for me. Thank you Helios.
PS Friday and Saturday night the club below has bass-heavy music till 3:30am, but you can sleep through it and it's not a huge problem.