According to Michigan State University, Germany has the highest density of flat green roofs. As the picture demonstrates, flat green roofs can be simple in design, and can easily fit into both the man-made and natural landscape.
If one googles "green roof Germany," one will find article upon article about the rise of flat green roofs in the 1970s in Germany to combat storm water runoff. Having had friends in Germany, they told me how expensive water was and how the government was trying ways to capture water from roadways and other sources.
Hat's off to Germany and their flat green roofs! Notice there were no David Hasselhoff jokes?