It is named after Costa Rica's national hero, Juan Santamaría, a drummer boy who died in 1856 defending his country against forces led by William Walker, an American filibuster. The airport is located in Alajuela Province, 20 kilometres (12 mi 11 nmi) west of downtown San José. Juan Santamaría International Airport ( Spanish: Aeropuerto Internacional Juan Santamaría) ( IATA: SJO, ICAO: MROC) is the primary airport serving San José, the capital of Costa Rica.