We loved staying at Guillhermo’s apartment. It is very stylish and located in a great area with lots of nice restaurants and cafes nearby. We only had to take the train when we went out of madrid as all our main sites were within 30mins walk (or less). The courtyard is really beautiful too. This place does have a couple of minor quirks (front key can be fiddly; get Antonio to show you the trick at check in, the intense shower!) but I would definitely stay here again!