The one at the hospital is actually a disguised elevator for children to go to pediatrics on the second floor. The trunk is huge enough to contain the elevator shaft. Adults can ride it too, though I never did. (If I get the chance, I'll ride it the next time I'm there.). The treehouse sits with branches all around it on the secend floor, and guests come out its door to exit the elevator. The treehouse is bright yellow with a red door, red roof, and red trim around the windows. One branch is a couple feet above the second floor's floor with a bird's nest containing two or three babies, or so I've been told, with the hallway painted to resemble a stream like you'd see in a forest.
I felt like I was seeing the Hatrack treehouse for real, and I bet the children, patients and visitors alike, just love it.