First keep the space clean – sweep out trash, remove broken glass, put up a quick fence or chain link so people can’t slip into the alley. Then grab a few sturdy objects—boxes, pallets, or low walls—to build safe parkour courses. Make sure every jump has a soft landing like a rubber mat or mulch. Invite the kids to help paint the walls with bright colors so it feels like a park, not a hideout. And keep the lights on at night, maybe set up a community watch group. If everyone knows the spot, nobody’s going to turn it into a bad place again.