I live near a small, possibly private, airport. Every day there are small planes flying low over the neighborhood in circles for over half an hour. They appear to just be flying for recreational purposes. They're also coming in and leaving low enough to be seen through the tree/wire lines and directly over houses. I have seen the airport's grass runway, and it is quite large, so I don't see why the plane wouldn't be able to just land without circling so long. Why would a pilot do this and is it legal? Also, this is not a rural area, it is a highly-populated city.