Ayub National Park is the largest park in the twin cities, a long strip of green that runs along the edge of the Margalla foothills and forms one of the more pleasant breaks available from the congestion of central Rawalpindi. Named after Field Marshal Ayub Khan, who served as Pakistan's first military ruler, the park contains a small zoo, a lake, picnic grounds, and walking paths that get genuinely quiet midweek.
It is a popular weekend destination for families from both Rawalpindi and Islamabad, and on Fridays and public holidays it fills up considerably. The zoo is modest by international standards and the animal welfare situation is not ideal, which is worth knowing in advance. The lake and the green space around it are the main draw. If you want fresh air without driving up to Murree, this is the most accessible option in the area.