My friend and I had an amazing stay in Madrid! The apartment is located in a cool and quite district (Lavapies) in which we felt relaxed and not overwhelmed by noises. Also, you literally have all of the must-visit places at 15 mins by foot which is a huge PLUS. :) The apartment in itself is super clean, functional, minimalist! We had all we needed to enjoy our holidays.
Highly recommend and will definitely come back there if ever I come back to Madrid.