Set up in 1955, this charitable foundation and hive of musical, artistic and scientific activity was one of few such organisations in Spain for a good many years. These days the Fundación Juan March remains a key player in Madrid's classical world, putting on around 150-200 free concerts per year. These usually consist of soloists or chamber ensembles and take place on Mondays at midday and Wednesday evenings from 7pm (the most popular slot, with better-known professional musicians and broadcast on Radio Nacional) as well as some Saturdays at midday with younger musicians. The concert hall seats 300; when it fills up a second hall with a big screen is opened, and then the bar. The programme in general is pretty much free from restrictions as it does not depend on ticket sales; there is a leaning towards Spanish composers, but with a lot of flexibility. Take in some good art exhibitions while you're there - in 2007 these include a look at the work of Roy Lichtenstein.