Our daughter was working in Madrid for three months and found this charming little posada right in the heart of MAdrid. The Cava Baja is full of character. Apparently the King of Spain eats in the restaurant a few doors away nearly every week.
The Posada was a converted winery and they had cleverly created glass floors so you could see down into the cellars. WE stayed up the top in a wonderful room with lods of character, with a bath with a jacuzzi [as well as a shower].
Charming bar with a great choice of wines. The breakfast was good.

We booked a double Corrola room at Posada del Leon de Oro and they kindly ungraded us to a balcony room (first floor) instead.

We were very warmly welcomed by the reception staff who whipped out a Madrid map and showed us a clear route to catch all the main sights in Madrid and places to catch a bite.

The room was very clean and it was quite nice to people watch from the balcony. The furnishing is very quirky and modern. Lots of mirrors in the room also made the place seem very spacious. The room also boasts a Sony Bravia TV. I didn't watch any TV, so I don't know if there were any English channels.

The bathroom light blew out on the second night, but after we alerted the staff the following morning - it was replaced by the time we got back to the room that evening.

If I had to pick up on a couple of negatives:

1) we were allocated a twin room instead of the double that we originally reserved. However saying that, we weren't too fussed and we liked the room enough. After all, a hotel room is a place for a good night's sleep. Which leads me to my next point...

2) We would hit the hay around 12am most evenings and we would be able to hear the murmour of people chatting outside the local tapas bars (the hotel is right next to lots of great tapas bars/restaurants). If you are a light sleeper, I would suggest that you request a non-street facing room... or time your bedtime with the locals'. Personally, I can sleep through anything so this was not really an issue for me.

Location wise, it is within a few minutes walking distance to most of the main sights of Madrid (Sol, Plaza Major, the Royal Palace, Mercado San Miguel), a couple of supermarkets and lots of tapas restaurants. La Latina metro station is only a 3 min walk away.

This is truly an excellent place. When we were booking the hotel, we did a google search to find some very terrible looking pictures of the property a few years back. My first dose of advice is to ignore these pictures as this hotel has been transformed into a true gem. This is the definition of a boutique hotel with a modern twist as all the rooms are very modern looking in terms of layout, design, and furniture. The best part of the hotel is probably the street that it is on. It comes alive in the nighttime with dozens of tapas restaurants and bars serving hundreds of people during the traditional after 9pm tapas time. Random parades of people will erupt with music coming from all angles. It was terrific. The hotel is also decently close to the metro. The bar and restaurant are gorgeous with glass floors and other neat Spanish decor. This is an expensive place but it is worth every penny if you want an authentic Madrid experience.

Choose this hotel based on Tripadvisor reviews and really find a small boutique hotel of 5 stars.
Location, staff were great and room was clean and large enough for being a small hotel.
When they say to write them in advance , as I did, they really answer all your emails and will honor your requests, including early check in, if available.
And yes, of course I will stay again in this beautifull boutique hotel in my next visit to Madrid.