Hostal Olga is perfectly located in the City Center, clean and has nice staff. Also got free upgrade to better room. Close to bus stop for Airport bus and Metro. Famous Prado museum nearby. Reception is open 24h so no need to check in before 23:30 as mentioned in booking confirmation. As I was late at the Airport I took a taxi for 30€ to be on time but that was not necessary - Bus close and only 5€.