Puerto Nariño

The Amazonian village of Puerto Nariño, 47 miles (75km) upriver from Leticia, is an inspiring example of human coexistence with nature. Here, cars are banned (the only two vehicles are an ambulance and a truck for collecting recyclables), rainwater is pooled in cisterns for washing and gardening, and electricity comes from the town's fuel-efficient generator, which runs only until midnight. Every morning, citizen brigades fan out to tidy up the town's landscaped sidewalks, and Puerto Nariño's ambitious recycling and organic-waste management programs would put most world cities to shame.