What does it take to be a truly green city today? Is it simply the effective use of natural and renewable energies? Or is it more about providing outdoor green space for residents? And how about transportation? More than four decades after the first Earth Day, the online magazine luxurydefined of Christie’s International Real Estate identifies seven cities that are leading the way toward a greener world.

Oslo, Norway

The European Commission awarded Oslo the prestigious European Green Capital title for 2019. The designation was created to reward a city’s commitment to, and efforts toward, improving its urban environment and boosting awareness of the need for environmental change at a city level, which is especially important given that more than two-thirds of Europeans currently live in urban areas.

Vancouver, Canada

A world-renowned city for green thinking and living, Vancouver has a sterling reputation in environmentalism: the lowest greenhouse gas emissions in North America and more than 300 LEED-certified buildings (as reported by the city council’s Green Vancouver initiative). Residents will enjoy Vancouver’s 200 green spaces, including the 1,000-acre Stanley Park—one of the greatest urban parks in the world.

Copenhagen, Denmark

The Danish capital consistently ranks among the world’s greenest cities. A former European Green Capital (a title awarded by the European Commission in 2014), Copenhagen has been recognized globally for its environmental urban planning and its bicycle- and pedestrian-friendly streets. More than a third of its people bicycle to work or school, and the city aims to increase that to 50 percent to reach its goal of being carbon neutral by 2025. 96 percent of residents have access to green space in 15 minutes or less—all 5,584 acres of it.

Amsterdam, Netherlands

Arguably the most bicycle-friendly city in the world, Amsterdam is reportedly home to more bikes than people. Since residents prefer to use cycles over their cars, Amsterdam’s many attractions are bike and pedestrian accessible, including the Hermitage Amsterdam, the Dutch outpost of Russia’s St Petersburg museum. The gardens of the Rijksmuseum, known as the “green outdoor gallery,” are also popular and showcase several historical garden styles and include a number of newer features, including a 19th-century green house with so-called “forgotten” heirloom vegetables and a water maze.

Zurich, Switzerland

Thanks to its strong commitment to reduce pollution from vehicles, the promotion of cleaner forms of transport, and low levels of air pollution, Zurich finished first in the Sootfree Cities ranking, an initiative of the Soot Free for the Climate Campaign, which grades the efforts of 23 major European cities to improve air quality. The Swiss city has a long-term objective of becoming a 2,000-watt society by 2050. What does this mean? Zurich has set the goal for its citizens to consume only 2,000 watts of energy per capita—the amount acknowledged globally as sustainable.

Essen, Germany

Essen, in Germany’s Ruhr Valley, is a city transformed from a coal and steel town into one of the greenest cities in the world. The European Green Capital of 2017, Essen’s eco credentials include overall energy performance, biodiversity, green urban areas, waste production and management. The city’s target is to cut carbon dioxide emissions to 40 percent by 2020, as reported by the European Commission. The city has an outstanding public transportation system and its bicycle lanes have been expanded citywide.

Sidney, Australia

Sydney was the first local council to be certified as carbon neutral under the Australian National Carbon Offset Standard. The Sustainable Sydney 2030 program aims to make the city more global, connected, and green over the next decade. Part of the city’s vision is to lower emissions and create more pedestrian zones and transportation routes, linking the CBD to the suburbs. The Smart Green Business program, implemented in 2014, has so far helped small- and medium-sized businesses improve their environmental performance, saved over 200 million liters of water, and diverted 2,400 tons of waste from landfills.