I recently attended a lecture by Tony Kirkham of Kew Gardens, titled from Inspiration to Installation.

What inspired him to work with trees, from playing conkers as a child to becoming a tree climber at Kew and then worked his way up the tree / ladder and has had some amazing botanical adventures all around the world. His latest accomplishment is an aerial walkway, 18m above ground, through tree top canopies at Kew enabling visitors to get up into the trees.It is well worth a visit! Do go if you have a head for heights.
http://www.kew.org/visit-kew-gardens/garden-attractions-A-Z/Xstrata-Treetop-Walkway.htm