Yanko Design has by far the coolest concept for buildings ever! Having a huge jungle gym on the roofs of buildings on a city wide span would be awesome! Things like this should be required for plans of all new buildings from now on, and, should be incorporated into all exsisting buildings. Think of the fun you could have at 30 stories up. Endless ammounts thats waht! Just, make sure this stuff is made well, cause falling from 30 stories is pretty much guarenteed death.