If composting is second nature and you grimace when you see people leave the grocery store with plastic bags (*shudders*), then where you spend your money while traveling is probably important to you. Here is a list of the most sustainable cities in the world. What does that mean? These are locales that have shown their dedication to renewable initiatives (e.g., bicycle infrastructure, efforts to lower emissions, electric vehicle incentives, etc.). Of course, overall quality of life plays a part, too. From Seoul to Stockholm, these destinations are making a positive impact on people and the planet.