During my trip to Costa Rica I spent half my time in San Jose, the capital of Costa Rica. It lies within the Central Valley alongside the other cities of Alajuela, Heredia, and Cartago. The Central Valley being where a large proportion of the Costa Rican population reside.
As far as the museums go I would've liked to have visited the Pre-Columbian Gold museum but it was closed at the time, and I don't think I was much aware of the National Museum. I did visit one museum and that was the Museo de los Niños, a museum which was really for children hence the name in Spanish. I believe it was a converted former prison.
Some landmarks which I passed by included the Parque Nacional, Parque Morazan, the National Theatre of Costa Rica, and Parque Central. The National Theatre of Costa Rica is located bang in the centre of San Jose and was first built in 1891 and then opened in 1897. It is still used to host performances to this day.
Besides the museums one could visit, there really wasn't a lot to do in San Jose (or in the centre anyway) apart from eating in restaurants or checking out the souvenir shops. One mildly amusing moment I remember was seeing a black guy (whom I assumed was homeless) who had a bushy silvery beard and was walking around with some kind of spear, he reminded me of Neptune!