Madrid-Barajas Airport (IATA: MAD, ICAO: LEMD) is the main international airport serving Madrid in Spain. It is the country's largest and busiest airport, the world's 11th busiest airport (2008) and Europe's fourth. It opened in 1928, and has grown to be one of the most important aviation centres of Europe. Located within the city limits of Madrid, just 9 km (5.6 mi) from the city's financial district and 13 km (8.1 mi) northeast of the Puerta del Sol, Madrid's historic centre. The airport name derives from the adjacent district of Barajas, which has its own metro station on the same rail line serving the airport.