Ideally located at the centre of Madrid, in a very nice area : you will reach a bunch of museums in usually 15 minutes using Metro. And still, you will enjoy a relative quietness compared to the main streets of Madrid.
The flat itself is immaculate, and you'll find all the needed comfort inside.
Last but not least, the owner is a very sympathetic fellow, who will provide good advices about places to visit, and where to eat very well for reasonnable fares.
It's very rare that i give a 5 star opinion on holidays locations. But this one definitely deserves it.