METRO AT THE AIRPORT by DAO
The easiest, fastest and cheapest way to get into Madrid from the Airport is to take the Metro. It is located right inside the airport, downstairs in Terminal 2. There are signs throughout all terminals directing you to the Metro Station. Metro trains service the airport between 6:00 am and 1:45 am every day. The Madrid Metro system is modern, efficient and covers most of the city. Metro Line 8 runs from the airport towards the centre (direction Nuevos Ministerios), but passengers have to change at Mar de Cristal (Line 4) to reach the most central destinations. Tickets are purchased from cashiers before you can get past the barriers. Look here for more information:
Madrid Barajas International Airport Ground Transportation