The City Council of Madrid has organised a series of free activities for the summer in both the Retiro Park and the Casa de Campo. The events are organised for both adults and children under the ages of 8 and mainly take the form of strolls around certain areas of both parks; though one activity includes a trip to a bird and butterfly centre. For more information, download this pdf Itinerarios Verdes from the Madrid City Council website or call them on 91 639 7969 between the hours of 9 a.m. and 2 p.m.