Alex M.
Yelp
I really liked this place. Entry fee was only 3 euros, I think. We got in free with the National Museum Card (which you can buy at the Prado or other large museums- gets you in free to all the national museums of Spain).
You enter the museum and get a guide book which is very helpful. You follow the guidebook through the traditional rooms of the house- vestibule, antechamber, salan, ballroom, living room, antechamber to chapel, chapel (and there's a Goya in the chapel!!!), boudoir, bedroom (ladies and man's) children's playroom (with a very sad statue of a dead child), smoking room, bathroom (with a king's upholstered toilet stool- I wish I could remember which king.)
The empire furniture was stunning, and I really enjoyed the paintings. The rooms with the "country people" paintings were especially interesting. If you have time, this is quite a nice place to visit and you will learn a lot in a short time. It reminds me a lot of the fully furnished canal house museums in Amsterdam- you really get a feel for what it must have been like to be rich in Madrid in the past.
The area around it is quaint- and it's not a bad walk from this museum to the archeological museum (which is in back of the national library).