Trees...I love them and have several fond memories of them. At the house I grew up in there was a beautiful Maple in the front yard. I'd climb up as high as I could often hauling things up with me like lunch, books, notebooks & pens. I'd sit up there for hours on end. In our back yard was a massive Box Elder Tree. We nailed wood to the side to make it easier to climb. It was to tall to go very high but my brother rigged up a zip line from it to another tree, we'd zip back and forth, loads of fun!
When my kids were little we had a tree that I let them climb. My oldest son, who was about 8, hauled wood up the tree to make platforms for them to sit and stand on. I thought it was ingenious and creative, looking back it was probably pretty dangerous. My kids spent hours in that tree and under it with the garden hose creating rivers in the dirt.
My brother lived in a house for a bit that had the perfect tree for climbing. At night we'd climb out a 2nd story window into the tree and sit, talk, laugh, listen to the night noises, look at stars and marvel at fire flies.
Here's a couple recent tree memories. First up a trip to Portland Oregon. They have very taaaalllll trees there.