The Hostel doesn't really have any signage, so locating it can be tricky. The Area to the left (as you face the entrance) is quite sketchy, drug taking, gang-like behaviour (we even witnessed a fight).
So take care when leaving the building.
I was in Room 316 - A previous review stated the tiled floor was broken back in May, it's still not fixed as of June 14/17.
Rooms are ok, very little means of keeping cool (no fan or A/C. One of the Toilets was out of order and vending machine in the communal area was seemingly broken.
Walls are quite thin so you can hear most of what's going on in other rooms.
I chose this as a cheap and cheerful option for a short break in Madrid and I wouldn't recommend anyone book this unless they were really desperate.
It's tired, there's nobody on site most of the time and at night it's quite sketchy if you're on your own.