This rental is in the heart of Madrid. During our stay, we were able to easily walk to all the big-name sites (Prado, El Retiro Park, the Royal Palace, the Puerta del Sol).
If you want a taxi, walk up the street, take a right and flag down one of the hundreds of Madrid taxis. Or walk 5-7 minutes to grab a subway.
There are food stores very near, and in Calle de Caballero de Gracia alone, about six restaurants. Check out La Gloria de Montera -- a white-tablecloth restaurant with lovely food.
We loved the contemporary decor. The living room is a fairly narrow space, but the kitchen area is roomy and the bedroom is lovely, with lots of storage space for clothing. For Americans used to larger quarters, be aware this is a small apartment, and four flights up a building with a tiny elevator. But why travel if everything is like home?!
A bonus (for us) is the church across the street -- we missed it at first, as it's eclipsed by a modern black-glass-window high rise and another tall building. Check out the interior -- lovely stained glass and murals. And the bells ring, somewhat mysteriously, for 41 chimes several times a day.
All in all, a great stay!