Short answer: Anywhere that is at least 20 feet wide by 44 feet long!
There are close to 8,000 places to play pickleball, with more than 30,000 pickleball courts, across the globe. Common places to play pickleball include senior-living communities, YMCAs, and local parks, schools, and recreation centers. To find a place to play pickleball near you, check out USA Pickleball's Places 2 Play website at https://www.places2play.org.
With that said, you can play pickleball on just about any hard surface that is at least 20 feet wide by 44 feet long. For instance, you can create your own pickleball court by marking out pickleball court lines (by using line kits or even chalk) and setting up a temporary net on any concrete area, wood or gym floor, or other hard surface, including a tennis or basketball court. You can also play pickleball on grass or clay tennis courts, as pickleball players are slowly testing the ability of pickleball to be played on these alternative surfaces.
The fact that you have the ability to play pickleball just about anywhere is one factor that makes the sport of pickleball so great. Pickleball is accessible and relatively inexpensive to play.