My sister and I absolutely loved our stay at Carmen's apartment - one of the highlights of our visit to Madrid. It is in an older building, but the room is completely renovated, which made for a very comfortable stay. It is very clean and has a modern design - I loved the little touches inside! Even though it is listed as a "private room", it feels more like an entire apartment because you get your own kitchen and a small living room area to sit around and relax. It was in a great location - right by the Atocha train station, a short walk away from the metro, and plenty of taxis right in front - very convenient! Carmen and her son were also very responsive - when I had questions or concerns, one of them would message back immediately. I highly recommend this place and would stay there again in a heartbeat. :)