Only two years old, its managers gave 12 top designers, including Norman Foster and Zaha Hadid, free rein over 12 separate floors.
The result is a bizarre wedding cake of utterly contrasting styles - in Marc Newson's corridors you'd be forgiven for thinking you were in hell, but you'll have to wear your sunglasses in the freezer-box of Zaha Hadid. Take a web-tour for an idea.
The gym, spa and small swimming pool on the top floor are perfect for some soothing New Year's Day exercise (remember that resolution?) - apparently they offer yoga and pilates on request.
And the quiet location - a cab ride to pretty much any of the main attractions - means you won't be tempted to break your head two nights running.
But you can get quiet locations and spas in most 5-star hotels - this one's special for its design. Don't expect it to be practical - there are reports that in some rooms you have to move the furniture to get at the fridge and so forth - but do expect a whole New Year's dose of style.
If you've spent all your Euros on New Year's Eve partying and can't afford the 155 ($228) double room starting rate, you should at least pop down a drink in the 13th-floor bar overlooking Madrid's lights and sights, then take the stairs down (or chat up the receptionist) for a tour.
By the time you get down to the Lágrimas Negras (Black Tears) restaurant designed by the French genius Christian Liaigre - better as a bar than as a restaurant, to be honest - you'll be needing another stiff drink to recover.
[Photo: Manu Contreras]