Love the idea of building this into our natural hill. * I have an idea of making a hill (with part of it dug out like this picture) and have logs buried in it with about wide exposed to act as a natural rock wall.
seating around tree - what if it rotated! that would be the hammer! make 2 half circles and mount them on legs with wheels then put around tree fix together with a rail of some kind so the wheels can only go in a circle.