Among its many virtues, one of our favorite city parks has some pretty cool art programming, quirkily called Mad. Sq. Art. The latest project, Pet Sounds, is a site-specific installation that will be up through the end of the summer. Artist Charles Long's largest public commission to date consists of a green network of railings supporting biomorphic forms that produce sounds and vibration when touched—just the kind of thing that's sure to keep mini parkgoers amused on their way to and from the playground. All ages.