Juan Santamaria International Airport is the primary airport serving San Jose, Costa Rica, and as such, is the primary airport for Costa Rica, as well. It is named for Juan Santamaria, a drummer boy who died in the war against the American filibuster William Wallace.
Like many or most airports, Juan Santamaria is located a distance away from the urban area it serves. In this case, it is located about 10 miles from the center of San Jose, in Alajuela Province, and is about two miles from the center of Alajuela itself. The airport is on the major highway between Alajuela and San Jose. It is also close to the Tren Interurbano line between Alajuela and San Jose, although the current schedules for that line don't make it convenient for a transport option.
Juan Santamaria airport also has a single terminal, and a single runway. Like other things in Costa Rica, I was somewhat surprised by the relatively small size of the airport. Costa Rica is a popular tourist destination for people from North America, Latin America, and Europe, and yet the airport is relatively small and basic. The waiting area for pre-security passengers consists of a single cafe with a few drinks and snacks. Past security, there are a few more restaurants, but is still pretty basic. Outside the gates, there is a parking lot full of taxis. None of this is terrible, but it is a bit underwhelming given Costa Rica's reputation as a luxurious international tourist destination.
As far as the functionality of the airport, it is a little better, with many domestic flights, as well as flights to Latin America, the United States and Canada, and Europe. I imagine that only having one runway means the airport might be at its limits for scheduling flights. Coming from the United States, it is somewhat difficult to get flights into Costa Rica, with most flights seeming to require transfers through Los Angeles, Dallas, or Miami. Which again, is not terrible, but seems to be in contrast to Costa Rica's image as an automagical tourist destination.
It also seems unlikely that the airport could be expanded where it is, since it is right in the middle of Alajuela and important commercial and residential buildings. A larger airport would have to be built somewhere else around San Jose, but I don't know any likely spots.