Let your kids set the agenda on your next family fun day by heading to the Imagination Playground near South Street Seaport. A prominent architect laid out the space, but the kids will have plenty of input of their own. Watch their creativity flow as they manipulate a collection of big blue blocks into shapes and structures all their own. Mats, fabrics, and wagons add to the possibilities. On hot days, sprinklers and fountains provide refreshment and other elements for play. If engineering isn’t enough, there’s plenty of space for running and climbing, too. Younger members of the family won’t be overlooked as there’s a massive sandbox, with shovels and buckets ready for little hands. Specially trained Play Associates provide gentle suggestions without interfering with the child-directed philosophy. While the kids explore, parents can chill in the shade, enjoying the views of tall ships and ancient bricks, the best of New York’s past and present just steps away.