People have speculated that trees on top of buildings are not feasible in reality. Completed in 1995, the ACROS building in Fukuoka by Emilio Ambasz is a 25 year old example of a building as a forest!
The building steps back gently from the adjacent Tenjin Central Park into lush green terraces which are open for the public to explore as a vertical extension of the park!
Images by Jonathan Choe