Konstantinos's place is the perfect spot for a wonderful stay in Madrid. Right in front of the Caixaforum Musem, and just a few minutes' walk away from the Prado and the Retiro park, this fun apartment has the best location you could wish for. Barrio Las Letras is a beautiful neighbourhood. Safe and fun, with plenty of cafes, bars and restaurants.
My boyfriend and I stayed in Madrid for a month and we found everything we needed (and more!). Konstantinos is very responsive and he took great care of us, so I would say he is not only a great host but also a wonderful human.
The only downside is that not much natural light gets in during the day, also the area can get quite noisy even during the night-time. However, Madrid is a vibrant city so it's the price you pay for being right in the city centre.
Highly recommended and we will surely be back!