ImpactCool Green Cities: Smart Projects in Copenhagen, Portland, Paris & MoreNina Strochlic06.02.13ImpactCool Green Cities: Smart Projects in Copenhagen, Portland, Paris & MoreFrom a Day Without Cars and gardens atop shopping malls, a look at smart projects from around the world.Nina Strochlic06.02.13 8:45 AM ETCorbis (2), AP, Getty Green never goes out of style. Around the world, cities are emphasizing sustainability and focusing on long-term environmental impacts. From bike-sharing projects to rooftop gardens to carless days, these metropolitan centers are leading the pack in all ways green. Click through for some of the coolest projects on the planet. Stan Honda/AFP/Getty The meteoric rise of the CitiBike has only just begun! At the end of May, 330 highly anticipated bike-sharing stations had been successfully installed around Manhattan and Brooklyn, with thousands of bikes available for rent. But maybe that was the easy part. Now, those crazy, er, environmentally conscious bikers now have to navigate New York traffic. But, along with the environmental aspects, the benefit of being able to skip cab gridlock and subway delays is a big plus. Stefano Amantini/Corbis Once known for its polluting industries, Chicago has reinvented itself as a pioneer in building with environmental effects in mind. Former Mayor Richard M. Daley created the Chicago Center for Green Technology, which became the first of its kind to score a LEED Platinum rating. Chicago's 24-acre Millennium Park is one of the forward-thinking city's most versatile spaces. It hosts Frank Gehry's Jay Pritzker Pavilon, and, of course, the reflective Cloud Gate, known by locals as "the bean," a tourist favorite. Don Ryan/AP Oh Portland, you're always ahead of the curve. Back in 1971, Oregon became the first state to implement a deposit system for cans and bottles. Since then, the state's biggest metropolis has kept this innovative spirit alive through the local-food movement, light-rail services, hundreds of miles in bikeways, and 10,000 acres of parks. Portland's latest too-good-to-be-true plan is to combine the city's light-rail trains, trolleys, forest trails, and sky tram into "the 4T trail" that would show off the city's views. Fernando Vergara/AP Around the world, cities have been trying to inspire residents to ditch four wheels in favor of two (or other variations of non-car transport). But in Colombia, the effort is taken very seriously. Here, cyclists ride along an empty avenue that leads to the airport in Bogota during a Day Without Cars, on Feb. 7, 2013. Cars were banned from the city for the day, and residents of the capital walked, biked, or used public transport to get to their destination. It was the 13th consecutive year for the experiment, which serves to promote alternative transportation as a way to reduce smog. Khan Tariq Mikkel/Polfoto, via AP Sometimes simple is best. In the waters off Copenhagen, this takes the form of a wind turbine park. And it's one of many. In 2008, Denmark's parliament aprroved plans for a 400-megawatt offshore project, which was slated to provide energy to 400,000 homes. The Danes have the windmill prediliction in their blood—they've been investing in wind power since the 1970s. In 2001, they opened the world's largest offshore windmill park, which generated 40 megawatts of electricity for 32,000 people. Bertrand Gardel/Corbis Paris may be known for its beautiful architecture, crusty pastries, and less-than-welcoming denizens. But the city is also making an effort to green itself. In April, the city's largest roof garden was opened, atop of the Beaugrenelle shopping mall. It will include a collective garden and bird nesting boxes. Putting the "green" into "green buildings" is the Quai Branly Museum, pictured here, which boasts a "vertical garden," made of a sheet of vegetation grown hydroponically in felt pockets. John Harper/Corbis A city with 250 acres of gardens in the center of it? Singapore's Gardens by the Bay is just that. The park consists of three waterfront gardens: Bay South Garden, Bay East Garden, and Bay Central Garden. Supertrees are tree-like structures that dominate the Gardens' landscape with heights that soar up to 160 feet in the air. Other features include a "cloud forest," "flower dome," and themed, educational-oriented gardens. The entire project has been planned with comprehensive environmental impact in mind.