Howdy Craig! Congrats on your 6 year old climber. My youngest son also loves to climb. Having not been to our Bloomington store I reached out to a friend who works there. According to her and her climbing team that lower tower is 40ft.
Here are a few other "Pinnacle Facts" from the Bloomington team:
"Enclosed in glass, the 55 foot REI Pinnacle is the tallest freestanding indoor climbing structure in the Midwest. Replicating the look and feel of natural minnesota basalt, the concrete shell was fabricated from moldsof the rock formations found in the St. Croix River Valley."
Thanks for your note!