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!!!

It looks like this tiny hotel might have seen better days, though it's still a nice place to stay for travelers on a budget. I chose it out of an old Lonely Planet guide. The hostel is small--about 10 single and double rooms--and is located on the second floor of an apartment building. The staff are very friendly and kind, and only speak Spanish. The place is very bare bones--bed, bath, tv, closet--but clean and comfortable. Location is excellent for sightseeing, night life, and shopping. Price is good, too--50 euro/night.

Have stayed twice at this hostal, and the first time it was an excellent experience. Had a nice big double, newly renovated and unbelievably nice bathroom (to this price). I believe there is two rooms of these high standards, and this is truly a great bargain.

However, when we were there last time, we were given a really small room on the floor above. And they charged the same as the room mentioned above. Very disappointed, we were told that the big rooms had been rented to someone else....

Great location close to bars and shops and Plaza Sta. Ana, and just 5 minutes to walk to Puerta del Sol, the most vibrant place in the centre of this incredible city.

Suitable for budget minded travellers, who speak a little Spanish. (The staff don't understand more English than absolutely necessary....)

Recommended to young people in their 20s or 30s, as there are loads of bars and noisy nightclubs in the area. However, you cannot hear the noise from your room if not opening your window (please note that I have never stayed there during summertime or when it's hot).