Thank you Carmen for hosting us.
The apartment looked very modern and clean, and it had a really nice bed. The location is very useful: so close to the station and also on walking distance of nice musea (Prado/Reina Sofia/Thijssen) and close to a street with nice restaurants and bars. Too bad we couldn't leave our luggage there for the day but Carmen recommended us a place at the Atocha station with luggage lockers so it was no problem at all!