Caesar met us at the flat and showed us around, then he pointed out on local maps where the local shops etc were, recommended some cafes and restaurants, and gave us some ideas for day trips. This was very kind and much appreciated.
The apartment is modern and clean, and is really well situated for the Prado and other museums, and also for the main railway station.
It is a very good base if you are spending a few days in Madrid and want to see as much as possible.