My husband and I recently stayed at Sergio’s place on our first trip to Madrid. Natasha - delightful! - met us and gave us some excellent tips, including suggestion to visit literary quarter, which we loved but otherwise wouldn’t have known about. The apartment is super clean and stylish and in a location convenient to everything. It’s also in between two metro stops so it’s a short walk with your luggage so no need to take a taxi if you don’t want to. Highly recommend the apartment.