Trees for small gardens: Fagus sylvatica Atropurpurea Group, copper beech, is a large tree, but it can be pleached to provide a screen. Tie in young stems to form a framework, then trim annually. Photo by Sarah Cuttle.
Copper beech leaves. Saw some yesterday; one of nature's quiet glories.
copper beech | Fagus sylvatica purpurea - Copper Beech Plants | Trees and Hedging
Love the stone path and the plinths. By Arne Maynard, Chelsea Flower Show 2012
Purple Beech Hedging Shrub (Fagus sylvatica Purpurea)
FOCAL POINT PATH WITH PLEACHED FAGUS SYLVATICA PURPUREA - COPPER BEECH. Arne Maynard design. Chelsea Flower Show 2012.
Was thinking again about the tree and your circular wall idea, and worrying about the roots, then remembered tree seats. This is from googling 'half round tree seat'...
copper beech spring
Pleached copper beech in the The Laurent Perrier garden, designed by Arne Maynard, also won a gold medal at Chelsea Flower Show 2012.
copper beech | The birds unfortunately quickly harvest the berries from this tree ...