http://www.tylerarboretum.org/

In Media, PA looks like it is a FABULOUS Arboretum. 
Go to Site
Click on VISIT Tab
Then click on: Kids and Families
and it tells you all about :

Totally Terrific Treehouses

Crooked Goblin Shack

Kids love visiting the house that Goblins built. Unfortunately, goblins are not very good builders because everything they do is crooked. They walk in crooked lines, they talk a crooked language called goblindeegoop, and everything they create is crooked. Created by Mark Cook Landscape and Contracting, LLC for the 2010 Philadelphia Flower Show and generously loaned for the enjoyment of Tyler’s visitors.

Troll Bridge

This elegant bridge, complete with hidden troll dwelling, is based on the tale Three Billy Goats Gruff. Kids love crossing the bridge, but must be careful not to wake up the grumpy sleeping troll! Created in 2010 by Parris Bradley and John Stovicek using recycled materials.

Magical Path

Venture down this woodland path to find villages, hamlets, and castles, created for gnomes, fairies, wizards, goblins, and other magical folk. You never know which magical creature may be hiding nearby to enjoy Tyler’s hospitality!

Fairy House Building Area

Gnomes, fairies, elves and the rest of their friends are having trouble finding suitable housing due to vanishing local woodlands and meadows. You are invited to help by creating a special home in our enchanted community. Supplies for fairy cottages, gnome homes, and elfin mansions are available at the Gnome Depot, which stocks a full inventory of sticks, cones, bark, nuts, and other natural materials that will be needed for construction. Your creation will stay at the Arboretum for use by visiting wee folk, but we hope you will build magical sanctuaries at your house too!

What Lies Beneath?

Tucked away beneath the trees, this mysterious old door begs the question “What Lies Beneath?”A troll? A wizard? A family of elves or hobbits? A mythological protector of the woods? It’s up to you to decide! To answer that question, visitors of all ages are encouraged to use their imaginations to create a story or poem inspired by this unexplained door. Submit your story to “The Tyler Arboretum Writing Project” at www.tylerarboretumwritingproject.com. Created by in 2010 Pine Street Carpenters, Inc.

Wizard Herbology Workshop

Wizards are very powerful and can create all kinds of magical potions and spells. They often use plants and one of the important courses taken by apprentice wizards is called Herbology. Apprentices learn to identify many of Mother Nature’s plants so that they know which ones to use to help people, birds, butterflies, animals – and other Wizards! Visitors who venture inside will see some of their recipes – and the Wizard’s Magical Ball.

Kids’ Nature Play Area

An area created just for the young ones, this is a place for kids to dig in the dirt, climb up the mulch mountain, jump on stumps, or walk the log balance beam. A perfect place for lots of fun, movement, and discovery. Bring a lunch or snack to enjoy on the nearby picnic tables.

Cool Frogs

These whimsical frog sculptures arrived at Tyler as part of the original tree house exhibit that celebrated the fact that trees are indeed home to many creatures – including tree frogs! An instant success, our friendly frogs draw young visitors like a magnet and kids love to climb them, name them, and get their picture taken with them.