This ** restaurant is located in a beautiful historic building, just off Plaza de Espana. It is small (so make reservations in time!), but has a nice atmosphere. The staff is attentive, and speaks English well.
The menu is outstanding, the dishes beautiful - sometimes spectacular - and in just the right portions (although the pace is somewhat high - which makes sense if you have 7-10 courses). The sommelier is knowledgeable and picks unusual wines (like the one from Canary Islands).
They give you the menu and wine pairing in print when you leave (even when you have made changes to the set menu), so you can read up on wines or dishes when you get home.
All in all an outstanding experience.