Lovely small hostal close to Santa Ana which has great bars and restaurants.
Comfortable internal room with tiny bathroom, clean and with safe and TV.
Sound does travel through these buildings so ear plugs are a must.
Central and easy to walk to most galleries and sights. Handy for Sol and Seville metro stations and easy airport connection.

For a centrally located hostal in Madrid i don't think you could do much better than this one. I wasn't expecting much for the price (special offer in July 32€ for a single room) but I actually got a double room with a private bathroom on the 1st floor. It was air conditioned, well-maintained and spotlessly clean. Double glazing, persianas and thick curtains meant that a good night's sleep was had despite overlooking a busy street. Easy walking distance from Sol Metro station. Staff confirmed my booking by personal email as I requested as I don't trust booking websites! I will definitely use this hostal again!

The staff is really nice and helpfull. We book a twin room but at the end a friend of us decided to join us in Madrid. We asked to have one more bed in the room and they help us very carefully.
The room was not really big but large enough for 3 beds.
The bathroom was clean.
The location is perfect: 3 minutes walking to Puerta del Sol. Calle del Principe is one of the most popular street for movida.
It's not possible to have breakfast at the hostel, but you can easily find a good caffeteria in the area.
Good value for money!

Amazing kindness!!!They tried so much to help despite their poor english.
We stayed for 3 days.The hostel is in the 2nd floor(without a lift-
not a big deal)of a building in a narrow street 30m from Plaza Santa Anna.Less than 100m from Sevilla metro station(red line).

The room was small but cosy,as well as the bathroom.The were
cleaning and we had new towels every day!!The small balcony was looking upon the street.Without breakfast(very common in
this categorie in Madrid),but just outside the building you can find
whatever you like almost all day-night long.
As soon as we arrived we got 3 keys.For the room door,the hostal
door and the building entrance door in the street.Very safe.
The noise(you are in the heart of the Madrid nightlife) was not
really a problem(double balcony doors).Happy young people
walking up and down the street-not drunk,not shouting.

If you want a decent and economical base,without luxury, to explore Madrid ,yes,go and stay in San Isidro.
It's position is very convinient.You can walk all over the historical center-everything is nearby.To Prado-Reina Sofia-Thiessen
museums is a 10min walk.To plaza Mayor is a bit less.
Of course you can use the metro.Safe,frequent,clean.
If you arrive in Barahas airport and you plan to use many times the metro,you can buy a 10-trip ticket(8 euros.Outside airport costs 7 euros.The 1 euro difference is the extra charge for going to or leaving the airport)from the metro desk or the automatic machines just before the metro entrances.
My wife and I finished 3 of those in our 3-day staying!!!