AbstractAs the opportunities for new territories become more limited, the only way is up. Mitchell Schwarzer explores the dizzying heights of the ‘last biotic frontier’ of arboreal architecture with its high platforms, walkways and canopy craft. Challenging in construction and engineering terms, the tree canopy also requires engaging with a different atmospheric and climatic range to those conditions encountered at ground level. Copyright © 2010 John Wiley & Sons, Ltd.