Argentine artist Tomás Saraceno currently has his largest solo presentation to date installed at Berlin’s Hamburger Bahnhof called Cloud Cities. The incredible exhibition consist of twenty balloon structures suspended by complex webs that stretch across the massive space that used to be a train station. Each balloon houses its own ecosystem that all together, create a utopian garden. His installation invites visitors to move amongst them, with some making it possible to climb inside and float in space. Have you seen any green art lately?