I stayed in Pedro's place for two nights while I was waiting for flight out of Madrid. Chamartin is not in city center but was exactly what I needed to get good rest and a little bit closer to the airport than the city center. It was a nice, very safe neighborhood. With a 15 minute walk to the train station and 10 minute to the metro. Pedro was a great host. My flight landed in Madrid at 10pm, it took me about 20 minutes by metro to airport to get to his house with a short 10 minute walk after. He greeted me with a small, but perfect meal since it was late. His apartment was clean. He offered me food in the mornings and offered great conversations about the climate of Spain and local recommendations.