The apartment of Sylvia is very well located in Madrid: close to El Retiro, Metro station only 2 minutes away; you can find a market, bakeries and many opportunities to eat out at any time, and still the area is very quiet.
It is an apartment big enough for 2-3 people, completely well-furnished and clean, with a small balcony where the sun gets in in the morning.
Communication with Sylvia was unproblematic and she was very flexible with hand-in of keys and returning them.
Very recommended. We'll be back!