Its a perfect place to explore Madrid.
The apartment is very complete, the terrace is lovely (as is the airco and the elevator!)
We didn't meet Carlos, but he guided us great by email and whattsap, and a friend welcomed us.
Very close is the Matadero, a unique cultural venue, Madrid Rio, a beautiful park, and Mercado Guillermo de Osma, a covered food market.
We would love to stay again at Carlos'.