First, a few words about hosts. They were absolutely great!!! Sylvia and Noelita (I hope I didn't mix the name,if yes, sorry) almost immediately answered all my mails, texts and What's up messages. They waited till 1 am for our arrival! If there was any problem they resolved it instantly! They were very helpful and gave us necessary information and maps. There were all the basic things for low-cost airline travellers. The apartment itself is not for demanding people, but we just woke up there, ate breakfast and returned in the evening. It's 3rd floor but there's a lift. Air-conditioning works perfectly which was very important when it was 33-37 C outside. You live among real madrileńos, so if you are a light sleeper going to sleep early with the windows open, it's good to take earplugs. It's very close to Atocha station, Museo Nacional Centro de Arte Reina Sofía, Prado and Parque de El Retiro. There are naturally lots of bars and tapas around. A supermercado open till midnight, Lidl, etc.
I definitely recommend going to Toledo, Avila, Segovia and Cuenca.
If you are dedicated walkers, you don't have even to use metro. To go to Teleferico and from Campo home takes about 20 kms. Menu del dia costs from €9 to 12. Teachers have free entrance to most museums, Royal Palace and botanical park!