more than 4000 trees are planted on top of a world war 2 bunker in hamburg, germany. on may 15th 2023 the green roof project is

urban greening pauli bunker building city modern green roof rooftop garden sustainability environmental horticulture gardening nature cultivation plant ecologically citycenter eco growing sky tower architecture hamburg european europe germany famous skyline panorama cityscape industry stpauli flak concrete german historic more than 4000 trees are planted top world may 15th 2023 project still under construction germany construction