The walls are up! With lots of help from Andy, Ben and Ryan. Everything went pretty much according to plan - two people on the ground hoisted the walls up to two people up in the treehouse who pulled them the rest of the way. Then we drilled them into the platform and to each other at the corners. Seems very sturdy. The back wall with the huge opening will get a window. The other two windows will remain open, but Julia has asked for shutters. Roof is next - it's covered with a tarp for now.