A lovely apartment right in the centre of Madrid which means that you can walk to most attractions within 30 minutes. There's also lots of great bars and restaurants within 5 minutes walking.
Check in was really easy using a dropbox just around the corner from the apartment. Marta and Arturo even arranged a taxi for me from the airport. Which was very helpful as I was arriving quite late. Communication was very easy.
The apartment was immaculate and well-equipped. I'd definitely stay there again.