I went in this hotel for a couple of days during summer. The location is perfect. It is just nearby Plaza Mayor and other sightseeing in Madrid such as the Opera, the Royal Castle. The building, which is antique, is beautiful as well in the inside as the outside. FYI, there is a charming old elevator!

I asked for a room at the highest floor possible with a view on the Plaza San Martin and I had it. The room was spacious and the view breathtaking.
Breakfast was excellent. The breakfast room is at the top floor and has a beautiful view as well.

The only thing was that the receptionist was a bit rude... Except of that, our stay was great.
I warmly advise you to go at this hotel. It is a great value for money!

Nice medium size hotel. Very near to the Callao metro station and Puerta del Sol. We stayed at one of the junior suites. It was not large but adequate, clean and comfortable.
From the airport : you can use shuttle buses to reach Fuente de Cibeles ( 2 euros) and then walk 30 meters to the metro station of Banco de Espana. (Buy tourist pass ticket for 1 to 7 days, it would be the best choice to reacheverywhere in madrid) and then take line2 (red) to Puerta del Sol station. Walkto the north (calle de preciados) turn left in 100 meters. If you need ask someone plaza san martin:)
Room tip:
Choose front side room and if possible a junior suite ;)

I had a slightly more mixed experience in certain regards, unfortunately, than other reviewers here. The rooms themselves, as well as cleanliness and room amenities were good, but the service was decidedly more inconsistent.

The location, as everyone has said, is excellent. As another user has recommended, it is quite easy to take the airport express line (yellow bus) to Atocha Renfe or Plaza De Cibeles and then a taxi from there to this hotel. The cost for the bus is 2 euro and the cab should be around 10 euro. If you book a junior suite, please know that most face the outer square and the noise may be excessive depending on your tolerance level! Amenities are fine, even smaller suites are quite spacious though some of the bathrooms may be cramped (as it was in my situation -- I initially was given room 510). Another helpful tip picked up from another reviewer here was to ask for a map from the front desk, as well as a WiFi access code for internet access on your wireless device.

I had troubles sleeping the first night, because the noise drifting up from street level was louder than anticipated. At 4am I went down to the night manager and asked to change rooms, which he graciously and kindly accommodated me in doing (room 415). It faced outwards to a small, very quiet side street and I was grateful for it. The bathroom was quite decent, good water pressure and instant hot water -- not always a given!

Service was mixed, and the least consistent. Because I downgraded from a more expensive suite to a smaller one on my first night, one of the concierge managers (I'm sorry I didn't get her name) kindly told wait staff that it would be included free of charge as a result. This actually was unnecessary, as I was perfectly willing to pay and had inquired as such. So, it was gratefully appreciated. A few days later however, I went down to have breakfast (I hadn't taken advantage of it since that first morning) quietly and politely waiting to inquire about breakfast -- and was completely ignored by the wait staff. One girl actually stared at me as she walked past, but did not say a word. I had to speak with the manager at the concierge desk. When I went to pay for breakfast afterwards (I had thought it was included, but didn't bother making a fuss) thankfully a different girl took my payment. I don't know why it would play into things, but I guess being a younger male solo traveller I don't give off an air of affluence and wealth = ). This shouldn't really affect service though, as I'm a paying client regardless. It was really rather disappointing, and were it not for the friendly and helpful night concierge manager (muchas gracias, David!) I would probably have ranked the service a notch lower, in all honesty.

Still, I wouldn't dissuade anyone from staying here, as the rooms, cleanliness and general amenities are all good. Location is fantastic and only a block away from El Corte Ingles, a large shopping complex where you can buy any necessities you need, and close to Plaza Mayor and Sol. It's a bit further away from the 'art triangle' but again, with the several metro stations close by (Callao, Opera, Sol) transit and making your way around is not an issue.

We stayed 7 nights at Intur Palacio San Martin and what a joy it was! The hotel is located within a walking distance from many of the Madrid attractions: Monasterio de las Descalzas Reales is virtually next door, the Royal Opera & Royal Palace, Plaza Mayor are less than 10 minutes away, as is Puerta del Sol. Il Corte Ingles - a store with everything - is a few hundred metres down the road. In fact we walked everywhere: Prado, Thyseen-Bornemisza, Park Retiro, even Museo Reina Sofia which is a bit further away... There is a good selection of eateries, coffee shops and restaurants near the hotel. Don't miss Chocolateria San Gines for its amazing hot chocolate and churos - it is two minutes away from the hotel. As the hotel is so centrally located there is no shortage of good shops, whether you are looking for boutiques, Spanish souvenirs, or quirky items. The staff at the hotel were friendly and helpful. Our room was fairly spacious, with a great bathroom. It was very clean and the room maids did an excellent job of maintaining it fresh and welcoming. The room was overlooking the lobby and was incredibly quiet, in fact, we had some of the best night sleep anywhere in the world! A tip: some taxi drivers seem to find it a bit difficult to find the hotel - just ask them to take you to Monasterio de las Descalzas Reales, one of Madrid's visitor attractions. The hotel door is 20 metres from it. I cannot recommend this hotel highly enough. We'll sure be back next time we are in Madrid.