Belen's flat was cozy, clean, and very stylish :) It is very close to the Prado museum, the Retiro park and the train station. You can also walk to the puerta del sol, plaza mayor and all other touristic sites. Belen recommended us a nice restaurant nearby with great food too. There is no elevator so it was a challenge carrying our luggage up to her place in the fourth floor, but the elevator is being installed at the moment so I think it won't be much of a problem in the future! I would definitely come back if I'm back in Madrid :)