Forget pollution, deforestation and species extinction. What we really need to worry about are ... cul-de-sacs.

Why? Cul-de-sacs — and the sprawl that creates them — are behind all those eco-problems, and are thus the greatest threat to our planet. That’s the message behind Built to Last, a three-minute video by First + Main and Paget Films which won a video contest hosted by the Congress for the New Urbanism and the Denver-based host committee for the organization’s 2009 conference.

Watch the funny-serious video to find out why you should fear cul-de-sacs and embrace new urbanism, a.k.a. walkable, bikable ‘hoods.

The filmmakers won free admission to the Congress for the New Urbanism’s conference, CNU 17, happening June 10 - 14 in Denver.