For the last twenty five years, America has built-up the suburbs. But now Americans are beginning to rethink whether these communities are environmentally sustainable. Joining The Takeaway is James Howard Kunstler, one of the urban thinkers gathering in Denver this week for the Congress for New Urbanism. He’s the author of "The Long Emergency: Surviving the Converging Catastrophes of the 21st Century."

In Denver, Colorado, a group of urban planners and architects gather this week to debate urban design. How can suburbia and downtown get closer? Joining The Takeaway from Denver is Ellen Dunham, the Director of the Architecture program at Georgia Institute of Technology and the co-author of "Retrofitting Suburbia: Urban Design Solutions for Redesigning Suburbs".

Like many cities, Denver is struggling to connect its suburbs to its downtown, and to create a new kind of city center. Continuing our series on the New Urbanism, The Takeaway talks to Matt Dellinger. He talks about the city's light rail project and the attempt to design and define new communities.

Follow along on The Takeaway's Urban Safari series.

In the past 50 years, Denver has grown from a small city to a sprawling metropolitan region. With urban sprawl comes gentrification. The Takeaway caught up with Andres Duany, the founding member of the New Urbanism movement, to ask him about gentrification. How do you keep a neighborhood mixed, economically and socially?

Also, hear this bonus web-only interview we did with Duany on urban sprawl!

This week The Takeaway is examining Denver as a laboratory for how the American city and surrounding suburbs are changing. The so-called "new urbanists" are pushing for more walkable, mixed-use (and mixed price) communities. They are gathering in Denver this week for the Congress on New Urbanism.

Matt Dellinger, transportation writer, joins The Takeaway to talk about who he's met and what he's learned while on safari in downtown Denver.

Follow along on The Takeaway's Urban Safari series.

This week The Takeaway looks at how cities are reinventing themselves for a world that doesn't depend on cars. Transportation writer (and Takeaway Contributor) Matt Dellinger is in Denver, CO, a town that has epitomized American urban sprawl. But Denver wants to reinvent itself and as the host city for the Congress on New Urbanism, the city is well on its way to streamlining its infrastructure. Also joining the conversation is Denver Mayor John Hickenlooper, to discuss how his city is reshaping itself.

Above is the 3-minute video that won the Congress for the New Urbanism's 2009 video contest. It's called "Built to Last" and it is from filmmakers First + Main Media from Julian, CA and Paget Films from Buffalo, NY (John Paget, Dr. Chris Elisara, and Drew Ward).

Follow along on The Takeaway's Urban Safari series.