You can do calisthenics as easily in a shady spot in the grass as you can on a mat in the gym. It’s just you and the shapes you make with your body to challenge it, with or without a prop. Activities that we can consider calisthenics include:
Yoga.
Pilates.
Many cross-training exercises.
Barre classes.
Exercises you may do in physical therapy.
Mat-based strength and conditioning classes you might take via your favorite exercise app.
Parkour (an activity where people use their environment in an acrobatic way, often jumping from point to point).
There are also athletes who practice urban calisthenics. Like parkour, these athletes use their environment. You’ll find them doing handstands and holding extreme strength poses.