Nativity façade, La Sagrada Família, Barcelona, Spain
"Barcelona has one of the lowest per capita greenhouse gas emission levels in the industrialized world, at under 4 metric tons of emissions per person per year (Houston is at 14.1 and Paris is at 5.2). And the city is still moving forward. 'In 2020 Barcelona could be a more environmentally conscious city,' according to Irma Soldevilla i Garcia of the Barcelona Energy Agency, 'in which careful energy consumption will be a regular part of people’s lives.'"
Learn more: Barcelona: Spain’s Ciudad del Sol