Slovenia has edged its way towards a more sustainable future with this incredible green-roofed skyscraper called the Kristalna Palaca. Also known as the Crystal Palace, the country's tallest skyscraper features all kinds of designer stores and cutting-edge energy solutions that bring its energy consumption in line with some of the world's most advanced eco-projects. In addition to producing a lot of its own energy with rooftop solar panels, passive design and truly innovative cooling programs reduce the building's overall energy consumption. And hey, it's not bad looking either!