The Holden Arboretum is located in Kirtland, OH, about a half-hour east of Cleveland. While “arboretum” may not be the first word that comes to mind when thinking of fun outings for your kids, this one definitely needs to be on your radar screen. Not even sure what an arboretum is? Here’s a definition from their Visitor’s Guide: “A living museum, an arboretum is a collection of woody plants, with plants labeled, catalogued and mapped.” Holden Arboretum is one of the largest in the country. It has 3,500 acres with gardens and collections comprising 600 of those acres.